JPH11314883A - Safety device of tower crain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the excessive winding and the winding shortage of a winch easily and securely without forming a force to increase the posture variation of a tower boom and a jib. SOLUTION: In order to lift and let fall a jib 3 folded at the front side of a tower boom 2 together with the boom 2, operation levers are operated at a time. A boom hoisting winch 4 is driven at the speed according to the operating amount of an operation lever for boom hoisting, so as to lift and let fall a delivery tower 2 including a boom hoisting rope 5. The drive of a jib hoisting winch 10 is controlled to make the relative angle of a swing lever 7 to the boom 2 controlled to make into an optimum value, by the control signal from a control device 30. The jib hoisting speed is controlled optimum, consequently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a tower crane having a tower boom and a jib.

[0002]

2. Description of the Related Art A tower crane is provided with a jib that can be folded at the tip of a tower boom. After the crane operation is completed, when transporting, first raise a boom hoisting rope with a boom hoisting winch to erect the tower boom. State,
Lower the jib hoisting rope with the jib hoisting winch, fold the jib forward and fold it to the front side of the boom, and fix the folded jib to the boom with a clamp. After that, the boom hoisting rope is lowered with the boom hoisting winch, and the boom integrated with the jib is turned down to the front of the fuselage.However, the rotation center of the boom and the feeding position of the jib hoisting rope by the jib hoisting winch are different. Therefore, when the boom hoisting rope is lowered and the boom is turned down, the jib hoisting rope is in tension. Therefore, in order to prevent a large tension from acting on the jib hoisting rope, the jib hoisting rope is extended from the jib hoisting winch and lowered at the same time as the boom hoisting winch is lowered. Then, disassemble the tower crane that has fallen into the tower body, tower boom, and jib,
Transport them with a trailer or the like. Also, when using a tower crane by assembling the tower boom and the jib on the tower body that has been transported, the boom hoisting rope was wound up with the boom hoisting winch and integrated with the jib as described above. When the tower boom is set in the upright state, the jib hoisting rope is loosened when the boom hoisting rope is rolled up and the boom is erected because the center of rotation of the boom is different from the retracted position of the jib hoisting rope by the jib hoisting winch. For this reason, the boom hoisting rope is wound up by the boom hoisting winch, and at the same time, the jib hoisting rope is also wound up by the winch so that the jib hoisting rope is not loosened.

[0003] In the above operation, if the rope is excessively wound by the boom hoisting winch or the jib hoisting winch, excessive tension is applied to each rope, and
Insufficient winding of the rope by each winch causes the rope to relax and cause the drum to wind up. In order to avoid such a problem, for example, Japanese Patent No. 2662421 discloses that the tension of a jib elevating rope is detected, and when the rope tension reaches a preset turbulence generating limit tension or breakage limit tension, a winch is detected. There is disclosed a tower crane safety device that stops the hoisting or lowering operation of the tower crane, thereby preventing the occurrence of rope turbulence and the damage of the tower attachment.

[0004]

However, in the method of controlling the driving of the winch based on the rope tension as in the above-mentioned conventional safety device, when the tower is raised or lowered, the rope tension is set to the turbulent winding limit tension. Since the tension fluctuates between the breakage limit tensions, a fluctuating tension acts on the rope so as to increase the posture change between the tower boom and the jib. As a result, irregular forces are applied to the clamp that integrates the tower boom and jib, making smooth undulating movement difficult, and if you forget to clamp, keep the posture change constant. Will be impossible to keep. In addition, control using upper and lower limits such as turbulent winding limit tension and breakage limit tension may cause momentary over / under tension to exceed the limit value momentarily for any reason. (This is called overshoeing) and can damage ropes and structures.

SUMMARY OF THE INVENTION It is an object of the present invention to enable a smooth up-and-down operation without exerting a force for increasing a posture change between a tower boom and a jib when the tower is raised and lowered. An object of the present invention is to provide a safety device for a tower crane that can reliably prevent shortage.

[0006]

Means for Solving the Problems (1) Referring to FIGS. 1 to 3 showing one embodiment, the invention according to claim 1 is characterized in that a tower boom 2 which rises and falls by raising and lowering a boom hoisting rope 5 is provided. , A jib 3 that rises and falls when the jib hoisting rope 11 is raised and lowered. The ratio of the hoisting / lowering speed of the jib hoisting rope 11 to the hoisting / lowering speed of the boom hoisting rope 5 is determined by an angle detecting means 31 for detecting the hoisting angle of the tower boom 2 and a value corresponding to the hoisting angle α of the tower boom 2. The above object is achieved by providing the control means 30 for controlling the hoisting / lowering speed of the boom hoisting rope 5 and / or the hoisting / lowering speed of the jib hoisting rope 11. (2) According to the invention of claim 2, the tower boom 2 raised and lowered by hoisting and lowering the boom hoisting rope 5 and the swinging lever 7 which rotates at the tip of the tower boom by hoisting and lowering the jib hoisting rope 11 move up and down. The present invention is applied to a safety device of a tower crane having a jib 3 which is provided. An angle detecting means 32 for detecting a relative angle θ of the swing lever 7 with respect to the tower boom 2;
And the control means 30 for controlling the hoisting / lowering speed of the boom hoisting rope 5 and / or the hoisting / lowering speed of the jib hoisting rope 11 so that the relative angle θ detected by the control unit 2 becomes a predetermined value θ1. Is achieved. (3) As shown in FIG.
Operating state detecting means 33, 34, and 35 for detecting an operating state for integrally raising and lowering the tower boom 2 when the operating state detecting means 33, 34, and 35 detect the integrated up-and-down operating state. And rope speed control by the control means 30. (4) The invention according to claim 4 is when the hoisting operation of the boom hoisting rope 5 and the hoisting operation of the jib hoisting rope 11 or the lowering operation of the boom hoisting rope 5 and the lowering operation of the jib hoisting rope 11 are performed simultaneously. In addition, the operating state detecting means 33 and 34 detect an integrated undulating operation state.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a configuration of a tower crane provided with a safety device according to an embodiment of the present invention. As shown in FIG. 1, the tower crane includes a crane main body 1, a tower boom 2 rotatably supported by the crane main body 1, and a jib 3 rotatably supported by the tip of the tower boom 2. Consists of FIG. 1 shows a so-called setup state in which the tower crane is being raised or turned over. In the setup state, the jib 3 is attached to the tower boom 2.
Are fixed to the front side by a clamp 13, and both are integrally raised and lowered in the A or B direction.

The crane body 1 is equipped with a boom hoisting winch drum 4.
The first boom connected to the tip of the tower boom 2 by winding or unwinding the boom hoisting rope 5 wound around
The tower boom 2 is raised and lowered via the pendant rope 6. A swing lever 7 is rotatably supported at the tip 2 b of the tower boom 2. This swing lever 7
Of the jib 3 through the second pendant rope 8
One end of a third pendant rope 9 is attached to the other apex via a guide roller 2a provided on the back side of the tower boom tip 2b.
The other end of the third pendant rope 9 is connected to a bridle device 12.
Attached to. A jib hoisting winch 10 is mounted on the crane body 1, and the swing lever 7 is rotated via a third pendant rope 9 by winding or feeding out a jib hoisting rope 11 wound around the jib hoisting winch 10. Is done.

As shown in FIG. 1, when the tower boom 2 and the jib 3 fixed by the clamp 13 are to be erected in the direction A, as described above, the boom hoisting rope 5 is wound and the jib hoisting rope 11 In this case, if the winding speed of the jib hoisting rope 11 is too high compared to the winding speed of the boom hoisting rope 5, the swing lever 7 rotates in the + θ direction with the tip 2b as a fulcrum. Excessive tension may act on the up-and-down rope 11 and the second and third pendant ropes 8 and 9, and the guide roller 2a and the clamp 13 may be damaged. Conversely, if the winding speed of the jib hoisting rope 9 is too slow compared to the hoisting speed of the tower boom 2, the swing lever 7 rotates in the -θ direction with the tip 2b as a fulcrum, and the jib hoisting rope 11 relaxes. Turbulence occurs in the jib hoisting winch 10 or the bridle device 1
2 may come into contact with the tower boom 2. As described above, the rotation direction and the rotation amount of the swing lever 7 with the tip 2b as a fulcrum, that is, the relative angle of the swing lever 7 with respect to the tower boom 2 depends on the winding speed of the jib hoisting rope 11 with respect to the winding speed of the boom hoisting rope 5. It reflects the validity of the speed. The present embodiment focuses on this point, and focuses on always controlling the relative angle of the swing lever 7 optimally irrespective of the hoisting speed of the tower boom 2.

In FIG. 1, a control device 30 is mounted on the crane main body 1, and a horizontal line H and a center of the tower boom 2 are mounted on the tower boom 2 as shown in FIG. A pendulum type earth angle meter 31 for detecting an angle α formed with the line L is attached. As shown in an enlarged view of FIG. 3, an angle θ between the center line L of the tower boom 2 and the swing lever 7, that is, the relative position of the swing lever to the tower boom 2 A counter angle meter 32 such as a rotary encoder for detecting the angle θ is attached.

FIG. 4 is a hydraulic circuit diagram of a tower crane equipped with the safety device according to the present embodiment. As shown in FIG. 4, the safety device includes a main pump 21 and a hydraulic motor 2 that rotates by pressure oil supplied from the main pump 21.
2, 23, the tower hoisting winch 4 and the jib hoisting winch 10 driven by these hydraulic motors 22, 23, respectively, and the hydraulic motors 22, 2 from the main pump 1.
Control valves 24 and 25 for controlling the flow of pressure oil to
Operating levers 26 and 27 operated to drive these control valves 24 and 25, respectively;
The pilot valves 26a, 26b, 27a, 27 for controlling the pilot pressure supplied to the pilot chambers 24a, 24b, 25a, 25b of the control valves 24, 25 in accordance with the operation amount of 27
b, and a hydraulic pump 28 for supplying pressure oil to the pilot valves 26a, 26b, 27a, 27b. Also, between the pilot valves 27a, 27b and the control valve 25, electromagnetic proportional valves (electromagnetic proportional pressure reducing valves) 29a, 29 for proportionally reducing the primary pressure from the pilot valves 27a, 27b to the secondary pressure.
b is provided, and the secondary pressure from the electromagnetic proportional valves 29a and 29b is controlled by a control signal from the control device 30 as described later. The operation levers 26 and 27 are provided with operation amount detectors 33 and 34 such as potentiometers, respectively.

FIG. 5 is a block diagram of a control device 30 incorporated in the safety device of the tower crane according to the present embodiment. As shown in FIG. 5, the control device 30 includes a ground angle meter 31 for detecting the ground angle α of the tower boom 2, a counter angle meter 32 for detecting a relative angle θ of the swing lever 7 with respect to the tower boom 2, Operation amount detectors 33 and 34 for detecting the operation amounts of the operation levers 26 and 27 for driving the winch.
And a control start switch 35 for instructing start of the up / down control of the jib 3 are connected. When various input signals are input to the control device 30 from these detection devices, the control device 30
Executes a predetermined calculation and outputs a control signal to the electromagnetic proportional valves 29a and 29b.

Next, the processing performed by the control device 30 will be described. In FIG. 5, the detection value from the ground angle meter 31 is
The target relative angle calculation unit 30a of the control device 30 takes in the
A target relative angle θ1, which is the optimum relative angle of the swing lever 7 with respect to the boom 2, is calculated. The target relative angle θ1 is determined in consideration of the rope tension acting on the guide roller 2a and the rope tension necessary for preventing turbulence. As described above, if the relative angle θ of the swing lever 7 is too large (eg, θ = θMAX), the rope tension becomes excessive, and an excessive load acts on the guide roller 2a, and conversely, the relative angle θ is too small. (For example, θ = θMIN), the rope tension becomes too small, and turbulence occurs in the drum. Therefore, the target optimum value θ
1 is determined to be a value that satisfies at least θMIN <θ1 <θMAX, and the rope tension at this target relative angle θ1 is an optimal value without excessively tightening or relaxing. If the weight of the swing lever 7 is taken into consideration, the magnitude of the rotational moment of the swing lever 7 with the tip 2b as a fulcrum varies depending on the magnitude of the boom-to-ground angle α. In addition, if the weight of the bridle device 12 and the ropes 9, 11 is considered, the direction of the force acting on the ropes 9, 11 changes depending on the magnitude of the boom-to-ground angle α. For example, when the boom-to-ground angle α is near 0 °, The own weight of the bridle device 12 acts in a direction that brings the bridle device 12 and the tower boom 2 into contact with each other. As described above, the direction of the force acting on the rope varies depending on the magnitude of the boom-to-ground angle α, and therefore the direction of the force acting on the guide roller 2a varies, and the stress generated on the guide roller 2a also varies. It is desirable that the angle θ1 is not a fixed value but a variable value according to the boom-to-ground angle α.

Therefore, in the target relative angle calculation unit 30a, the relationship of the target relative angle θ1 corresponding to the ground angle α of the boom 2 is determined in advance, and the ground angle meter 31 is determined using this relationship.
The target relative angle θ1 is calculated according to the detected value from. The target relative angle θ1 calculated in this way is subtracted from the relative angle θ actually measured by the counter angle meter 32 in the subtractor 30b, and the deviation e (= θ1−θ) is calculated. The deviation e is calculated by PI (proportional integration) by the calculator 30c, and the control signal I necessary to make the actually measured relative angle θ the target relative angle θ1 is calculated. The determination unit 30d receives a signal from the control start switch 35 and a signal from the operation amount detectors 33 and 34. When the control start switch 35 is on, any one of the following operations (a) and (b) is performed. Is detected, the switch 30 corresponding to the operations (a) and (b) is detected.
e or 30f is closed, and the electromagnetic proportional valve 29 is closed.
The control signal I described above is output to a or 29b. (A) Hoisting operation of operation lever 26 and operation lever 27
(B) Lowering operation of operation lever 26 and operation lever 2
When the control start switch 35 is turned off or the operation levers 26 and 27 are operated to other than the above (a) and (b), both the switches 30e and 30f are opened. As a result, the output of the control signal I is prohibited. The operations (a) and (b) in a state where the control start switch 35 is turned on mean the start of the setup work of the tower crane.

Next, the operation of the safety device of the tower boom equipped with such a control device 30 will be described more specifically. When the tower boom 2 is turned upside down to use the tower crane, first, the tower boom 2 and the jib 3 are connected by the clamp 13. Next, the control start switch 35 is turned on, and simultaneously the maximum hoisting operation of the jib hoisting operation lever 27 and the tower hoisting operation lever 26 are hoisted. By these operations, the switch 30e of the control device 30 is turned on, and the electromagnetic proportional valve 2 is turned on.
The switch 9a is controlled to switch from position b to position a so as to supply a secondary pressure (pilot pressure) according to the control signal I.
An operation lever 26 is provided in the pilot chamber 24a of the control valve 24.
The pilot pressure oil corresponding to the operation amount of the pilot valve 26
The control valve 24 is supplied from the pressure source 28 via a, and is switched to the position a. Accordingly, the pressurized oil from the main pump 21 is supplied to the hoist motor 22 via the control valve 24, and the tower boom 2 starts to stand up at a speed corresponding to the operation amount of the operation lever 26. The pilot pressure from the electromagnetic proportional valve 29a is supplied to the pilot chamber 25a of the control valve 25, and the control valve 25 is switched to the position a. Thereby, the pressure oil from the main pump 21 is supplied to the hoisting motor 23 via the control valve 25, and the rising speed of the jib 3 is controlled so that the relative angle θ of the swing lever 7 with respect to the tower boom 2 becomes the target relative angle θ1. Is done. In this case, the operation lever 27 is operated at the maximum in the winding direction, for example.
If the lifting operation of the operation lever 27 is slight, the primary pressure supplied to the proportional solenoid valve 29a as the pressure reducing valve is insufficient, and the secondary pressure (pilot pressure) required by the control valve 25 is supplied. May not be able to do so. In this regard, when the operation lever 27 is operated to the maximum, the secondary pressure (pilot pressure) supplied to the control valve 25 does not become insufficient. Therefore, the determination unit 30d of the control device 30 described above
Is the value at the time of the maximum operation.

When the tower boom 2 stands up to a predetermined angle,
The hoisting operation of the tower hoisting operation lever 26 is stopped, and the drive of the tower hoisting winch 4 is stopped. As a result, the switch 30e of the control device 30 is turned off, the control signal I to the electromagnetic proportional valve 29a is cut off, and the electromagnetic proportional valve 2
9a is switched to the b position. At this time, the hoisting operation of the jib hoisting operation lever 27 is also stopped. Next, the clamp 13 is removed, and in this state, the jib hoisting operation lever 2 is moved.
Only 7 is hoisted. Then, the pilot room 25a
The control valve 25 is switched to the position a according to the pilot pressure, and the jib hoisting winch 10 is driven. In this way, the jib 3 is raised upward while being separated from the tower boom 2 and is brought into a substantially horizontal state.

When the tower boom 2 in the upright state is to be turned down, first, the jib 3 is turned forward by the lowering operation of the operating lever 10 for raising and lowering the jib, and then the jib 3 and the tower boom 2 are clamped. . Next, the control start switch 35 is turned on, and the jib hoisting operation lever 27 is further turned on.
The lowering operation of the tower raising / lowering operation lever 26 is performed simultaneously with the maximum lowering operation. By these operations, the switch 30f of the control device 30 is turned on, and the electromagnetic proportional valve 29b is switched from the position b to the position a so as to supply a secondary pressure (pilot pressure) according to the control signal I. . As a result, the control valve 24 is switched to the position b in accordance with the operation amount of the operation lever 26, the hoist motor 22 is driven down, and the control valve 25 is controlled in accordance with the pilot pressure from the electromagnetic proportional valve 29b. b is switched to the position
3 is controlled, and the jib 3 and the tower boom 2 are turned over together. When the tower boom 2 is turned over, the operation of the operation levers 26 and 27 is stopped, and the setup work ends.

As described above, according to the present embodiment, the hoisting speed of the jib 3 is controlled so that the relative angle θ of the swing lever 7 with respect to the tower boom 2 becomes an optimum value during the tower hoisting operation. Damage to the structure due to excessive winding of the jib and irregular winding of the jib hoisting rope 11 due to insufficient winding can be automatically and reliably prevented, and the posture change between the tower boom 2 and the jib 3 is increased. A stable undulating operation can be performed without applying a large force. In addition, no excessive force acts on the clamp 13, and the clamp 13 may be unnecessary in some cases. Further, the target relative angle θ which is the optimum value of the relative angle θ
1 is calculated according to the angle of the tower boom 2, so that the rope 11
Can be dealt with without any problem even when the direction of the force acting on is changed. Furthermore, since only the jib hoisting speed is automatically controlled, the tower hoisting speed is determined by the operation amount of the tower hoisting operation lever 26, and the hoisting operation based on the intention of the operator is executed. Further, regardless of the switching control of the on / off type electromagnetic valve, the electromagnetic proportional valve 29
Since the jib hoisting speed is controlled by the pressure reduction control of a and 29b, a shock at the time of valve switching can be prevented.

In the above-described embodiment, the up-and-down speed of the jib 3 is controlled in accordance with the up-and-down speed of the tower boom 2. On the contrary, the tower boom 2 is controlled in accordance with the up-and-down speed of the jib 3. May be controlled.
Further, in the above-described embodiment, the hoisting speed of the jib 3 is controlled by controlling the relative angle θ of the swing lever 7. However, the present invention is not limited to this. For example, the winding-out feeding speed of the ropes 6, 11 is detected. Then, the hoisting speed of the jib 3 may be controlled so that the jib hoisting rope speed 11 with respect to the boom hoisting rope speed 6 becomes an optimum value corresponding to the hoisting angle α of the tower boom 2.

Further, in the above-described embodiment, the setup work is recognized by the signal from the control start switch 35 and the signal from the operation amount detectors 33 and 34. However, the present invention is not limited to this. Such a setup switch may be provided on the clamp 13, and the setup work may be recognized by turning on the setup switch. Alternatively, the setup operation may be recognized only by turning on the control start switch 35 or only by operating the operation levers 26 and 27 simultaneously. Further, the control valve 2
A pressure sensor is provided in each of the 4, 25 pilot lines, and the operation levers 26, 27 are determined by the values of the pressure sensors.
May be detected. Furthermore, a fully automatic switch may be provided in the driver's seat, and the tower hoisting operation may be started while controlling the boom hoisting speed and the jib hoisting speed to predetermined speeds by turning on the switch.

In the hydraulic circuit shown in FIG. 4, solenoid valves are provided between the control valves 24 and 25, which are pilot pressure supply lines, and the pilot valves 26a to 27b, and the boom 2 and the jib 3 are provided.
May be prohibited.

In the correspondence between the above embodiment and the claims, the control device 30 controls the control means, the target relative angle θ 1 shows a predetermined value, the operation amount detectors 33 and 34 and the control start switch 35
Constitute the operating state detecting means.

[0024]

As described in detail above, according to the present invention, the ratio of the hoisting / lowering speed of the jib hoisting rope to the hoisting / lowering speed of the boom hoisting rope, or the relative angle of the swing lever with respect to the tower boom, is the optimum value. The hoisting / lowering speed of the boom hoisting rope and / or the hoisting / lowering speed of the jib hoisting rope are controlled so as to be stable without applying a force that increases the posture change between the tower boom and the jib. Tower undulating operation can be performed. According to the third aspect of the present invention,
Since the rope speed is controlled when the jib and the tower boom integrally move up and down, normal work other than the tower ups and downs is not hindered. Further, according to the invention of claim 4, since the operation of raising and lowering the boom hoisting rope and the operation of raising and lowering the jib hoisting rope are simultaneously performed, the tower hoisting operation is recognized, so a setup switch and the like are separately provided. It is possible to reliably recognize the tower up-and-down operation without operating the switch.

[Brief description of the drawings]

FIG. 1 is a side view of a tower crane on which a safety device according to an embodiment is mounted.

FIG. 2 is an enlarged view of a part a in FIG.

FIG. 3 is an enlarged view of a part b in FIG.

FIG. 4 is a hydraulic circuit diagram of the safety device for the tower crane according to the present embodiment.

FIG. 5 is a block diagram of a safety device for the tower crane according to the present embodiment.

[Explanation of symbols]

 2 Tower boom 3 Jib 5 Boom hoisting rope 11 Jib hoisting rope 13 Clamp 30 Control device 31 Ground angle meter 32 Machine angle meter 33,34 Operation amount detector 35 Control start switch

Claims (4)

[Claims] 1. A safety device for a tower crane having a tower boom raised and lowered by hoisting and lowering a boom hoisting rope, and a jib raised and lowered by hoisting and lowering a jib hoisting rope, wherein an angle detecting means for detecting the hoisting angle of the tower boom. The hoisting / lowering speed of the boom hoisting rope and / or the ratio of the hoisting / lowering speed of the jib hoisting rope to the hoisting / lowering speed of the boom hoisting rope become a value corresponding to the hoisting angle of the tower boom. A safety device for a tower crane, comprising: control means for controlling a hoisting / lowering speed of a jib hoisting rope. 2. A tower crane having a tower boom raised and lowered by raising and lowering a boom raising and lowering rope, and a jib raising and lowering in response to a movement of a swing lever pivoted at a tip end of the tower boom by raising and lowering a jib raising and lowering rope. In the safety device, an angle detecting means for detecting a relative angle of the swing lever with respect to the tower boom, a hoisting / lowering speed of the boom hoist rope and a hoisting / lowering speed so that the relative angle detected by the angle detecting means is a predetermined value. And / or control means for controlling a hoisting / lowering speed of the jib hoisting rope. 3. The safety device for a tower crane according to claim 2, further comprising an operating state detecting means for detecting an operating state in which the jib and the tower boom are integrally raised and lowered, and the operating state detecting means is an integral part of the safety apparatus. A safety device for a tower crane, wherein the rope speed control is performed by the control means when an up-and-down operation state is detected. 4. The safety device for a tower crane according to claim 3, wherein a hoisting operation of the boom hoisting rope and a hoisting operation of the jib hoisting rope, or a hoisting operation of the boom hoisting rope and a winding operation of the jib hoisting rope. The safety device for a tower crane, wherein the operating state detecting means detects the integrated undulating operation state when the lowering operation is performed at the same time.