KR20040086033A - over load protector for crane - Google Patents

Abstract

PURPOSE: In using an air winch or hoist for a lift work, an air pressure supplied to an air motor is stopped automatically when an overload is applied. CONSTITUTION: An air motor(2)is connected to an air supplier. A drum is rotated by a planetary carrier fixed by a torque arm to wind a wire. A main control valve(5) is installed between the air supplier and the air motor to control air pressure. A control valve(6) is installed between the air supplier and the main control valve to control signal to convert the main control valve. A load detecting member detects load applied to the torque arm. A link(16) rotates when the load is over a limit. A limit valve(17) is installed to control air pressure supplied to a pilot valve.

Description

Overload protector for crane

The present invention provides a lifter that can stop the operation of the lifter even when operating a switch that supplies air pressure to drive the air motor when the load of the lifting object exceeds the rated load during the lifting operation using the lifter. Of overload protection device.

More specifically, the load of the lifting object is preset by the detecting means for detecting the load applied to each rope during hoisting operation using a lifter (refering to an air winch or hoist) using at least one rope. The present invention relates to an overload protection device for a double lift that can automatically stop supplying air pressure to an air motor when the load is exceeded to stop the lifting operation of the lift.

In general, an air hoist or winch is a hoisting air motor that is driven in a forward or reverse direction according to an air pressure supply source using an air pump or an air compressor, and an air pressure supply direction discharged from the air pressure supply source. And a control valve installed in the air passage between the air pressure supply source and the air motor to control the flow direction and stop of the air pressure supplied to the air motor when switching to the air pressure supply, and connected to the control valve to control the air pressure for switching the control valve. Equipped with up / down switch.

However, when the work hoist exceeds the preset rated load during hoisting, the aforementioned air hoist may cause an overload of the above-described air motor, which may shorten its service life, and may also result in inadvertent load. In case of excessive lifting of the workpiece, the air motor may malfunction or the wire to lift or lower the workpiece may be disconnected by the hook assembly, causing heavy accidents during heavy lifting. Will have

Therefore, an object of the present invention is to prevent the overloading of the parts by automatically blocking the supply of air pressure to the air motor when the lifting object load exceeds the rated load during hoisting using a lifting machine. The purpose of the present invention is to provide an overload protection device for a heavy lifter.

An object of the present invention is a detection means for detecting a load applied to a rope during hoisting operation by using a heavy lifting machine (referring to an air winch or a hoist) to prevent malfunction and failure by a non-electrical mechanical mechanism, It is to provide an overload protection device for a heavy lifter so as to improve the reliability.

It is still another object of the present invention to provide an overload protection device for a heavy lifter which allows the operation of the heavy lifter to be settled when lifting a workpiece exceeding the rated load so as to protect the operator from safety accidents due to falling of heavy weights. will be.

1 is a schematic hydraulic circuit diagram of an overload protection device for a heavy lifter according to an embodiment of the present invention;

2 is a schematic front view of an overload protection device for a heavy lifter according to an embodiment of the present invention;

3 is a schematic cross-sectional view of an overload protection device for a heavy lifter according to an embodiment of the present invention;

4 is a schematic side view of the overload protection device of the heavy lifter shown in FIG.

* Explanation of symbols used in the main part of the drawing

One; Pneumatic source

2; Air motor

3; Torque arm

4; drum

5; Main control valve

6; Control valve

7; carrier

8; Pilot valve

13; Safety valve

16; link

17; Limit valve

18; road

19; Elastic member

The object of the present invention described above is a hoisting air motor connected to a pneumatic source, a drum which is wired and rotated by a planetary carrier fixed to a torque arm, and is installed between the pneumatic source and the air motor and is supplied to the air motor. It is installed between the main control valve for regulating the air pressure, the control valve for regulating the signal pressure for switching the main control valve between the air pressure source and the main control valve, and is installed between the control valve and the main control valve and applied to the main control valve. In the overload protection device of a double lifter provided with the pilot valve which interrupts signal pressure,

Load detecting means for detecting a load applied to the torque arm;

A link rotated when the load applied to the torque arm by the load detecting means exceeds a predetermined load value;

It is achieved by providing an overload protection device for a heavy lifter, characterized in that it further comprises a limit valve interlocked at the time of the link rotation to control the air pressure supplied from the air pressure supply source to the pilot valve.

According to a preferred embodiment, the load detection means,

A rod installed on the limit valve so as to face the link, the rod contacting the rotating link to operate the limit valve when a load greater than a set value is applied to the torque arm, and a load applied to the torque arm exceeds a set value. In this case, it is provided with an elastic member which elastically biases as an initial state supporting the link to be pressed by the link.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are intended to be described in detail so that those skilled in the art can easily carry out the invention. This does not mean that the technical spirit and scope of the present invention are limited.

As shown in Figs. 1 to 4, the overload prevention device of the heavy lifter according to the present invention includes a hoisting air motor (2) for driving in the forward and reverse directions according to the air pressure supply from the air pressure source (1), and the air motor ( 2) a drum (4) wound by a carrier (7) fixed to the torque arm (3) is wound around the wire for lifting and lowering the workpiece during driving;

A main control valve (5) installed in the air passage between the pneumatic source (1) and the air motor (2) and intermittent to supply air pressure to the air motor (2), the pneumatic source (1) and the main control valve (5) A control valve 6 installed in an air passage between the control valves 6 for intermitting the signal pressure for switching the main control valves 5;

The pilot valve 8 is installed between the control valve 6 and the main control valve 5 to control the signal pressure applied to the main control valve 5, and between the pneumatic supply source 1 and the pilot valve 8. It is installed in the air passage and is applied to a heavy lifter having a safety valve 13 for intermitting the signal pressure supplied to the pilot valve (8) when switching, these will belong to the technical content used in the art, Note that detailed description of operation is omitted.

Therefore, the overload prevention device of the heavy lifter according to the preferred embodiment of the present invention includes a load arm means 15 for detecting a load applied to the torque arm 5, and a torque arm 15 by means of the load detector means 15. 5) When the load applied to the load exceeds the predetermined load value, the link 16 which rotates and the limit which interlocks when the link 16 rotates and interrupts the air pressure supplied to the pilot valve 8 from the air pressure source 1 are supplied. It further comprises a valve 17.

At this time, the load detection means 15,

The limit valve 17 is provided in contact with the pressing piece 16a formed at the end of the link 16 which is installed at the limit valve 17 so as to face the link 16 and is rotated when a load greater than or equal to the set value is applied to the torque arm 5. And an elastic member 19 which elastically biases as a starting state to support the link 16 so as to be pressed by the link 16 when the load applied to the rod 18 and the torque arm 5 exceeds the set value. ).

In the drawings, reference numeral 9 denotes a speed reducer, 10 a hinge pin for rotatably fixing the link 16, and 11 and 12 are initially set by the elastic member 19 when a load value within the range set on the torque arm 3 is applied. It is an adjustment bolt for fixing and holding the link 16 supported as a state.

Hereinafter, the operation of the overload protection device of the heavy lifter according to a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

a) The hoisting operation to lift the workpiece below the set load value by using lifter (air winch or hoist) is as follows.

As shown in FIG. 1, as the operator switches the control valve 6 downward in the drawing, after passing through the control valve 6 in which the air pressure from the air pressure source 1 is switched. , Via a pilot valve 8 installed in the air passage between the control valve 6 and the main control valve 5, is applied as a signal pressure to the main control valve 5 and is switched to the left in the drawing.

Accordingly, as the air pressure from the air pressure source 1 is supplied to the air motor 2 via the switched main control valve 5, the braking state of the mechanical brake 21 is released and the air motor 2 is released. Since it is driven in the forward direction it is possible to perform the hoisting operation to lift the predetermined workpiece by a hook (not shown) fixed to the wire wound on the drum (4).

On the other hand, as the control valve 6 is switched upward in the drawing, through the control valve 6 in which the air pressure from the air pressure supply source 1 is switched, the main control valve 5 is connected to the main control valve 5. It is applied as a signal pressure to switch it in the right direction on the drawing.

Therefore, as the air pressure from the air pressure source 1 is supplied to the air motor 2 via the switched main control valve 5, the braking state of the mechanical brake 21 is released and the air motor 2 Since it is driven in the reverse direction, it is possible to perform the work of lowering the predetermined work (work) by the hook fixed to the wire wound on the drum (4).

b) When the load of the work object being hoisted exceeds the set value, it is as follows.

1 to 4, when the load of the object lifted by the wire wound on the drum 4 exceeds the set weight, and the load more than the preset load value is applied to the torque arm 3. In addition, the link 16 is rotated in the clockwise direction with respect to the hinge pin 10 as a central axis in the drawing to press the elastic member 19 in the lower direction.

At the same time, as shown in FIG. 4, the pressing piece 16a formed at the end of the link 16 presses the rod 18 of the limit valve 17 to linearly move, thereby driving the limit valve 17. . At this time, the safety valve 13 is switched to the right direction in the figure.

Therefore, the air pressure from the air pressure source 1 acts as a signal pressure on the valve spring 8a opposite side of the pilot valve 8 via the switched safety valve 13, and is switched in the left and right directions in the drawing. . This closes the air passage 22 between the control valve 6 and the main control valve (5).

Therefore, even when the control valve 6 is switched downward in the drawing by the user, the main control valve 5 maintains its initial neutral state. Therefore, the compressed air from the air pressure source 1 As the supply to (2) is cut off, the air motor 2 is not driven.

As described above, when the load value of the lifting work object exceeds the set value, even when the control valve 6 is switched by operating the up / down switch (not shown) by the user, the air pressure supply source 1 Since the air pressure discharged from the air supply to the air motor 2 is automatically cut off, it is impossible to lift the workpiece exceeding the set load value.

At this time, the alarm is automatically generated to inform the operator that the load of the hoisted object exceeds the set value, causing the wire to be overloaded, and by operating the down button of the down / down switch by the operator Of course, the object can be lowered.

As described above, the overload protection device of the heavy lifter according to the present invention has the following advantages.

If the lifting load exceeds the rated load during hoisting using a heavy lifting machine, the service life is greatly extended by automatically blocking the supply of air pressure to the air motor to prevent overloading of the parts. The management cost can be reduced.

In addition, as a detection means for detecting the load applied to the rope during the hoisting operation by using a lifter, malfunction and failure can be prevented by a non-electrical mechanical mechanism, and the reliability of the load detection can be improved.

In addition, when lifting a workpiece exceeding the rated load, the operation of the lifter can be stopped to protect the worker from safety accidents due to the falling of heavy objects.

Claims (2)

A hoisting air motor connected to the pneumatic source, a drum that is wired and rotated by a planetary carrier fixed to the torque arm, a main control valve installed between the pneumatic source and the air motor to regulate the air pressure supplied to the air motor, The control valve is installed between the pneumatic source and the main control valve to control the signal pressure to switch the main control valve, and the pilot valve is installed between the control valve and the main control valve to control the signal pressure applied to the main control valve. In the overload protection device of the double lift equipped with: Load detecting means for detecting a load applied to the torque arm; A link rotating when the load applied to the torque arm by the load detecting means exceeds a preset load value; And And a limit valve interlocked during the link rotation to control the air pressure supplied from the air pressure supply source to the pilot valve. According to claim 1, The load detecting means; A rod installed on the limit valve so as to face the link, the rod being in contact with the link that rotates when a load greater than or equal to a set value is applied to the torque arm to operate the limit valve; And And an elastic member which elastically biases as an initial state to support the link so as to be pressed by the link when the load applied to the torque arm exceeds the set value.