JP2002003175A - Safety device for crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety device for a crane preventing swing of a boom. SOLUTION: A load detector 20 detecting a tension T of a boom derricking rope 8 supporting a boom 2 is provided. When the tension T drops below a designated value, the load detector judges that the boom 2 gets a tendency to swing due to a reduction of a support force of the boom 2, and outputs a control signal according to the rope tension T to an electromagnetic proportional pressure reducing valve 34. Accordingly, an inclination angle of a hydraulic pump 22 is controlled to restrict a derricking speed of the boom 2 and a jib 3. A sudden change of a moment load acting on the boom 2, thereby, is controlled to prevent swing of the boom 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crane safety device such as a tower crane or a crawler crane.

[0002]

2. Description of the Related Art As a crane safety device, for example, Japanese Patent Application Laid-Open No. Hei 10-45383 discloses a device that controls the driving of a boom in accordance with the boom angle. According to this, the boom speed is reduced when the boom undulation angle reaches a predetermined deceleration start angle, and the boom is automatically stopped when the boom speed reaches a predetermined stop angle larger than the deceleration start angle. As a result, the boom stops gently, and load deflection is prevented.

[0003]

By the way, the tension of the boom hoisting rope supporting the boom decreases as the boom hoisting angle increases, and the boom tends to swing. Particularly in a tower crane, the tower boom is often operated in a nearly vertical state, and when the jib is vigorously erected in this state, the tension of the boom hoisting rope rapidly decreases, and the tower boom is more likely to swing.
In such a case, the swing of the boom causes the load to swing, so it is necessary to suppress the swing of the boom.However, the device described in the public law described above controls the drive of the boom in accordance with the boom undulation angle, It does not prevent the boom from shaking.

[0004] It is an object of the present invention to provide a crane safety device that can prevent the boom from swinging.

[0005]

Means for Solving the Problems (1) Referring to FIGS. 1 and 2 showing an embodiment, the invention according to claim 1 comprises a crane body 1 and a shaft which can be raised and lowered on the crane body 1. The present invention is applied to a crane safety device having a supported boom 2. And a swing detecting means 20 for detecting a physical quantity T having a correlation with the swing of the boom 2, boom speed limiting means 21 and 34 for limiting the hoisting speed of the boom 2,
The above-mentioned object is achieved by providing the control means 35 for controlling the boom speed limiting means 21 and 34 according to the physical quantity T detected by the shaking detection means 20. (2) The invention according to claim 2 is a crane having a crane main body 1, a boom 2 pivotally supported on the crane main body 1, and a jib 3 pivotally supported on the tip of the boom 1 so as to be able to raise and lower. Applied to safety devices. Then, the swing detection means 20 for detecting the physical quantity T having a correlation with the swing of the boom 2, the boom speed limiting means 21 and 34 for limiting the undulation speed of the boom 2, and the physical quantity T detected by the swing detection means 20. The above-mentioned object is achieved by providing the control means 35 for controlling the boom speed limiting means 21 and 34 accordingly. (3) The invention according to claim 3 is the crane safety device according to claim 2, further comprising jib hoisting speed limiting means 21 and 34 for limiting the hoisting speed of the jib 3, and the control means 35 comprises: Controls the boom speed limiting means 21 and 34 in accordance with the physical quantity T detected by the control unit, and also controls the jib speed limiting means 21 and 34. (4) The invention according to claim 4 is the crane safety device according to claim 3, wherein the control means 35 controls the boom speed control means 21 and 34 and the jib speed control means 21 and 34 with different characteristics. Things. (5) According to a fifth aspect of the present invention, in the crane safety device according to any one of the second to fourth aspects, the crane safety device includes identification means 36 for identifying the sizes of the boom 2 and the jib 3, respectively. , And controls the speed limiting means 21 and 34 based on the size of the boom 2 and the jib 3. (6) According to the invention of claim 6, as shown in FIGS.
A crane body 1, a boom 2 pivotally supported on the crane body 1, a back surface of the boom 2 and the crane body 1
And a back stop 19 for preventing the boom 2 from tipping over. Then, the swing detection means 20, 51 for detecting a physical quantity T having a correlation with the swing of the boom 2, the expansion and contraction means 41, 42 for extending and retracting the backstop 19, and the physical quantity T, detected by the oscillation detection means 20, 51, The above-mentioned object is achieved by providing the control means 35 for controlling the expansion and contraction means 41 and 42 according to θ1. (7) According to a seventh aspect of the present invention, in the crane safety device according to the sixth aspect, as shown in FIG. 5, the swing detecting means detects the tension T of the rope 8 supporting the boom 2 as shown in FIG. The control means 35 includes the tension detector 2
The expansion / contraction means 41 and 42 are controlled so that the rope tension T detected by 0 becomes a predetermined value T0. (8) The invention according to claim 8 is the crane safety device according to claim 6, wherein, as shown in FIG.
When the swing of the boom 2 is detected by the control unit 1, the control means 35
However, the expansion / contraction means 4 extends the backstop 19.
1, 42 are controlled. (9) According to a ninth aspect of the present invention, in the crane safety device according to the eighth aspect, the swing detecting means includes a goniometer 51 for detecting the up-and-down angle θ1 of the boom 2.

[0006] 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.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. -First Embodiment- FIG. 1 is a side view showing a configuration of a tower crane provided with a safety device according to a first embodiment of the present invention. As shown in FIG. 1, a tower crane includes a crane body 1 and a tower boom 2 rotatably supported by the crane body 1.
And a jib 3 rotatably supported at the tip of the tower boom 2. The drum 4 of a boom hoisting winch, the drum 5 of a jib hoisting winch, and the drum 6 of a hoisting winch are mounted on the crane body 1.

The tip of the tower boom 2 is supported by a boom hoisting rope 8 via a first pendant rope 7. The boom hoisting rope 8 is wound around the boom hoisting drum 4 via the hanger 9, and the tower boom 2 is hoisted by winding or unwinding the boom hoisting rope 8 by driving the drum 4. A swing lever 10 is rotatably supported at the end of the boom. The end of the jib 3 is connected to a jib hoisting rope 13 via a second pendant rope 11, a swing lever 10, and a third pendant rope 12. It is supported by. The jib hoisting rope 13 is hung between the bridle 14 and the guide roller 15 and wound around the jib hoisting drum 5, and the jib 3 is raised and lowered by winding or feeding out the jib hoisting rope 13 by driving the drum 5. A hook 17 is suspended from the tip of the jib 3 via a hoisting rope 16. The hoisting rope 16 is connected to the hoisting drum 6 via a guide roller 18 at the end of the boom.
The hook 17 is moved up and down by winding or unwinding the hoisting rope 16 by driving the drum 6. A back stop 19 is provided between the back side of the boom 2 and the crane main body 1 to prevent the boom 2 from falling backward.

The hanger 9 is provided with a load detector 20 such as a load cell, and the load detector 20 detects the tension T of the boom hoisting rope. In FIG. 1, the larger the undulation angle θ1 of the boom 2 and the larger the undulation angle θ2 of the jib 3,
Is larger, the forward moment load acting on the boom 2 is smaller, whereby the tension of the boom hoist rope 8 supporting the boom 2 is reduced. When the tension of the boom hoisting rope 8 decreases, the supporting force of the boom 2 becomes weak, and the boom 2 easily swings. In this case, the change amount of the moment load acting on the boom 2 increases as the undulating speed of the boom 2 increases, and the change amount of the load becomes a vibrating force on the boom 2 so that the boom 2 is more easily shaken.
In the present embodiment, such rope tension T and boom 2
Paying attention to a predetermined correlation with the swing of the rope, the rope tension T
Is smaller than or equal to a predetermined value, the boom 2 is determined to be liable to swing, and the undulating speed of the boom 2 and the jib 3 is limited according to the rope tension T to prevent the boom 2 from swinging.

FIG. 2 is a hydraulic circuit diagram for a winch of a crane showing the configuration of the safety device according to the first embodiment. In FIG. 2, the hydraulic circuit of the hoisting winch is omitted. As shown in FIG. 2, the safety device includes a variable displacement hydraulic pump 22 whose pump tilt angle changes by driving a regulator 21, and a boom hoisting hydraulic motor 23 which rotates by pressure oil supplied from the hydraulic pump 22. And a hydraulic motor for jib hoisting, and these hydraulic motors 23,
24, a control valve 25, 26 for controlling the flow of pressurized oil from the hydraulic pump 22 to the hydraulic motors 23, 24, respectively; Operation levers 27 and 28 for inputting drive commands, respectively, and operation lever 2
Pilot valve 29 driven according to the operation amount of 7, 28
A, 29B, 30A, 30B and pilot valves 29A, 29
Pilot pump 3 for supplying pressurized oil to B, 30A, 30B
1, pressure switches 32A, 32B, 33A, 33B for detecting the presence / absence of operation of the operation levers 27, 28, and an electromagnetic proportional pressure reducing valve 34 (hereinafter referred to as an electromagnetic pressure reducing valve) for controlling pressure oil supplied from the pilot pump 31 to the regulator 21. And a controller 35 that outputs a control signal to the electromagnetic proportional valve 34. The hydraulic pump 22 is a motor 2
The horsepower is controlled so that 3,24 absorbed horsepower does not exceed the maximum horsepower of the engine. The winch circuit has drums 4 to 6 depending on the boom angle θ1, the jib angle θ2, and the hook height.
, A safety device such as a boom overwind prevention device, a jib overwind prevention device, and a hook overwind prevention device are provided, but these are not shown.

The controller 35 is connected to the load detector 20, the pressure switches 32A, 32B, 33A, 33B and the moment limiter 36. The moment limiter 36 limits the lifting load based on the boom length, the jib length, the boom angle θ1, the jib angle θ2, the rope tension T, and the like. The controller 35 executes the processing described below based on the input signals from these, and outputs a control signal to the electromagnetic proportional valve 34. Thus, the degree of pressure reduction of the electromagnetic proportional valve 34 is controlled. In this case, if the degree of pressure reduction of the electromagnetic proportional valve 34 is maximized, the regulator 21
The pressure supplied to the pump becomes the minimum and the pump tilt angle becomes the minimum q
min. When the degree of pressure reduction of the electromagnetic proportional valve 34 is minimized, the pressure supplied to the regulator 21 is maximized, and the pump tilt angle is maximized qmax. As described above, the pump tilt angle is set to the minimum qmin
To the maximum qmax.

The characteristics of the target pump tilt angle qa corresponding to the rope tension T are stored in the controller 35 in advance. One example is shown in FIGS. 3 (a) and 3 (b). FIG. 3 (a)
Fig. 3B shows the characteristics used when the boom is raised and lowered, and Fig. 3B shows the characteristics used when the jib is raised and lowered.
Decreases below a predetermined value (eg, T11, T21), the target pump tilt angle qa increases from the maximum qmax to the minimum q
reduced to min. The boom 2 has a rope tension T
In addition, since the swingability differs depending on the boom length and the jib length, that is, the shorter the boom 2 and the longer the jib 3, the more stable the boom 2 becomes and the harder it is to swing. In FIGS. 3A and 3B, a plurality of different characteristics are set according to the combination of the boom length and the jib length.

Here, the characteristics s11 and s12 are the characteristics when the boom length is the shortest and the jib length is the longest, that is, the characteristics under the condition in which the boom length is the least, and the characteristics s21 and s22 are the maximum boom length and the shortest jib length. In other words, the characteristics under the most swaying condition are shown, and the condition is such that the boom 2 easily sways from the characteristics s11 and s12 to the characteristics s21 and s22. In addition, the amount of change in the moment load acting on the boom 2 is larger when the boom is raised and lowered than when the jib is raised and lowered, so that the boom 2 shakes easily. Therefore, the characteristics s11 and s21 of FIG.
Comparing the characteristics s12 and s22 of (b), the target pump tilt angle qa in the characteristics s11 and s21 is smaller than the target pump tilt angle qa in the characteristics s12 and s22. That is, the target pump tilt angles q11, q2 at the rope tension T
1 is smaller than the target pump tilt angles q12 and q22.

In the present embodiment, predetermined characteristics (for example, s11) corresponding to the boom length and the jib length are selected from FIGS. 3 (a) and 3 (b) by processing in the controller 35 described later.
Is determined based on this characteristic s11, and when the rope tension T has reached a predetermined value (for example, T11) or less, it is determined that the boom 2 is likely to swing, and the pump tilt angle is controlled along the characteristic s11.

FIG. 4 is a flowchart showing an example of the processing executed by the controller 35. This flowchart is started, for example, by turning on an engine key switch. In step S1, it is determined whether or not the pressure switches 32A and 32B are on, that is, the operation lever 27 for raising and lowering the boom.
It is determined whether or not has been operated. If step S1 is affirmed, the process proceeds to step S2. If not, step S3 is performed.
Proceed to. In step S2, the boom length and the jib length are read based on the signal from the moment limiter 36, and the characteristics corresponding to the boom length and the jib length are described in FIG.
(A) is selected and the process proceeds to step S5. On the other hand, in step S3, it is determined whether or not the pressure switches 33A and 33B are on, that is, whether or not the jib operation lever 28 has been operated.
If not, it returns. In step S4, the boom length and the jib length are read based on the signal from the moment limiter 36, and the characteristics corresponding to the boom length and the jib length are selected from FIG. 3B described above, and the process proceeds to step S5.

In step S5, the rope tension T is detected based on a signal from the load detector 20. Then, step S
6, the target pump tilt angle qa corresponding to the rope tension T is determined from the characteristics selected in step S2 or step S4.
Is calculated. Next, in step S7, the electromagnetic proportional valve 34 is set so that the pump tilt angle becomes the target pump tilt angle qa.
And outputs a control signal, and returns. Thus, the degree of pressure reduction of the electromagnetic proportional valve 34 is controlled, and the pump tilt angle is controlled to the target pump tilt angle qa set according to the rope tension T, the boom length and the jib length.

Next, the operation of the first embodiment of the present invention will be described. (1) Boom hoisting In the hydraulic circuit of FIG.
Is operated from the neutral position, the pilot valve 29A or 29B is driven in accordance with the operation amount, and the pressure oil from the pilot pump 31 is supplied to the pilot port of the direction control valve 25 via the pilot valve 29A or 29B.
The direction control valve 25 is switched to the position A side or the position B side. As a result, the hydraulic oil from the hydraulic pump 22 is supplied to the hydraulic motor 23 via the direction control valve 25, and the boom hoisting drum 4 is driven up or down, and the boom hoisting rope 8 is wound or unwound, and the boom hoisting rope 8 is wound up. 2 undulates.

At this time, as described above, the rope tension T changes according to the boom angle θ1, and the rope tension T decreases as the boom angle θ1 increases. Here, when the boom length is the longest and the jib length is the shortest, that is, when the boom 2 is under the condition that it is most likely to swing, if the rope tension T is larger than the predetermined value T21 in FIG. Is determined not to occur, and the processing by the controller 35 sets the pump tilt angle to the maximum qmax. Therefore, when the lever operation amount is maximized, the boom 2 can be raised and lowered at the maximum speed. Rope tension T with increasing boom angle θ1
When the rope tension T becomes equal to or less than the predetermined value T21, it is determined that the boom 2 is likely to swing, and the pump tilt angle decreases along the characteristic s21 by the processing by the controller 35.
As a result, if both the engine speed and the load are constant, that is, if the pump discharge amount is constant, the supply amount of the pressure oil to the motor 23 is reduced, and the hoisting speed of the boom 2 is reduced. As a result, the change in the moment load acting on the boom 2 is reduced, so that the boom 2 is less likely to swing, and the swing of the boom 2 is prevented.

On the other hand, when the boom length is the shortest and the jib length is the longest, that is, under the condition that the boom 2 is hardly shaken, when the rope tension T is larger than the predetermined value T11 in FIG. The tilt angle is set to the maximum qmax, and when the rope tension T is smaller than the predetermined value T11, the pump tilt angle becomes the characteristic s.
Decreases along 11. In this case, T11 <T21, and the range of the rope tension T that limits the hoisting speed of the boom 2 is narrow, so that the hoisting operation of the boom 2 is performed efficiently.

(2) Jib Raising / Returning The boom raising / lowering operation lever 27 is returned to neutral to stop the boom 4 raising / lowering operation.
Is operated from the neutral position, the pilot valve 30A or 30B is driven in accordance with the operation amount, and the pressure oil from the pilot pump 31 is supplied to the pilot port of the direction control valve 26 via the pilot valve 30A or 30B.
The direction control valve 26 is switched to the position A side or the position B side. As a result, the hydraulic oil from the hydraulic pump 22 is supplied to the hydraulic motor 24 via the direction control valve 26, and the jib hoisting drum 5 is driven up or down, and the jib hoisting rope 11 is wound or unwound, and the jib hoisting rope 11 is wound up or fed out. 3 undulates.

At this time, the rope tension T changes according to the jib angle θ2 as described above, and the rope tension T decreases as the jib angle θ2 increases. Here, when the boom length is the longest and the jib length is the shortest, if the rope tension T is larger than the predetermined value T22 in FIG. 3B, it is determined that the boom 2 does not swing, and the pump tilts. The angle is maximal qmax, so that the jib 3 can be raised and lowered at maximum speed in this case. When the rope tension T decreases with an increase in the jib angle θ2, and the rope tension T falls below a predetermined value T22, it is determined that the boom 2 swings slowly. Decrease. Thereby, the supply amount of the pressure oil to the motor 24 is reduced,
The lifting speed of the jib 3 is reduced. As a result, since the undulating speed of the jib 3 is reduced, the change in the moment load acting on the boom 2 is reduced, and the swing of the boom 2 is prevented.

(3) Boom Raising + Jib Raising When the boom raising / lowering operating lever 27 and the jib raising / lowering operating lever 28 are simultaneously operated, as described above, hydraulic oil is supplied to the hydraulic motors 23 and 24, and the boom 2 and Jib 3 undulates. At this time, the pump tilt angle is controlled by the processing from the controller 35 along one of the characteristics shown in FIG. 3A according to the boom length and the jib length. As a result, the undulation speed of the jib 3 is made lower than that at the time of the jib undulation only, and the influence on the swing of the boom 2 is further reduced.

As described above, according to the first embodiment, the ease of swinging of the boom 2 is determined based on the rope tension T, and when it is determined that the boom 2 is likely to swing, the pump tilt angle is controlled in accordance with the rope tension T. Since the hoisting speed of the boom 2 and the jib 3 is limited, the change in the moment load acting on the boom 2 is reduced, and the swing of the boom 2 can be prevented. Further, since the control amount of the pump tilt angle is changed according to the boom length and the jib length, the boom 2 and the jib 3 are controlled in consideration of the influence of the boom length and the jib length on the swing of the boom 2. Speed control is optimally performed. Furthermore, since the characteristics of the pump tilt angle according to the rope tension are different between the boom undulation and the jib undulation, the swinging of the boom 2 can be efficiently prevented without unnecessarily restricting the undulating speed.

-Second Embodiment- A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a hydraulic circuit diagram for a winch of a crane constituting a safety device according to the second embodiment. The same parts as those in FIG. 2 are denoted by the same reference numerals, and the differences will be mainly described below. In the second embodiment, the back stop 19 is provided with a hydraulic cylinder 41, and the back stop 19 can be extended and contracted by driving the hydraulic cylinder 41. As shown in FIG. 5, the bottom chamber of the hydraulic cylinder 41 communicates with the hydraulic pump 31 and the variable relief valve 42, the rod chamber communicates with the tank, and the hydraulic cylinder 41 is driven according to the relief pressure of the variable relief valve 42. .
In the second embodiment, the control to reduce the pump tilt angle is not performed by the control signal from the controller 35, and the electromagnetic proportional valve 34 and the pressure switch 32A,
32B, 33A and 33B are omitted.

The load detector 20 and the moment limiter 36 are connected to the controller 35. The controller 35 executes the processing described below based on the input signals from these, outputs a control signal to the variable relief valve 42, and controls the relief pressure. As a result, the hydraulic cylinder 41 is driven to expand and contract, the pressing force acting on the boom 2 from the backstop 19 changes, and the tension T of the boom hoisting rope 8 changes.

As shown in FIG. 6, the relationship between the swingability of the boom 2 and the reference tension T0 is stored in the controller 35 in advance. Here, the swingability of the boom 2 is determined by a combination of the boom length and the jib length, and the boom length is the shortest and the jib length is the longest.
When the boom length is the longest and the jib length is the shortest, it is most likely to swing. The reference tension T0 means a target tension of the boom hoisting rope 8. In FIG. 6, the reference tension T0 is set so as to increase as the boom 2 is more likely to swing.

FIG. 7 is a flowchart showing an example of processing executed by the controller 35 according to the second embodiment. This flowchart is started, for example, by turning on an engine key switch. First, step S
At step 11, the boom length and the jib length are read in accordance with the signal from the moment limiter 36, and the reference tension T0 corresponding to these lengths is calculated from the above-described characteristic of FIG. Then
In step S12, the rope tension T is detected based on the signal from the load detector 20, and in step S13, it is determined whether the detected tension value T is equal to the reference tension T0. Step S13
When it is determined that T <T0, the process proceeds to step S14, in which a control signal for increasing the relief pressure of the variable relief valve 42 by a predetermined amount Δp is output, and the process returns to step S12. on the other hand,
If T> T0 is determined in step S13, step S1 is executed.
5, the relief pressure of the variable relief valve 42 is increased by a predetermined amount Δ
A control signal for lowering by p is output, and step S12 is performed.
Return to Then, when step S13 is affirmed, the process returns. As a result, the rope tension T is controlled to the reference tension T0.

With the above configuration, the safety device according to the second embodiment operates as follows. That is, when the tension T of the boom hoisting rope 8 decreases due to the raising operation of the boom 2 or the jib 3 and the rope tension T falls below the reference tension T0, the relief pressure of the variable relief valve 42 is determined by the processing from the controller 35 (step S14). Becomes larger. As a result, the pressure in the bottom chamber of the cylinder 41 increases,
The cylinder 41 extends, and the pressing force against the boom 2 increases. As a result, a tensile force acts on the rope 8 to increase the rope tension T, and the rope tension T is maintained at the reference tension T0. Further, even when the boom 2 or the jib 3 is stopped, the rope tension T is set to the reference tension T by processing from the controller 35.
It is kept at 0. Therefore, the boom 2 is stable without swinging even when an external force such as wind acts upon stopping.

On the other hand, when the rope tension T is larger than the reference tension T0, the relief pressure of the variable relief valve 42 is reduced by the processing from the controller 35 (step S15), whereby the pressure in the bottom chamber of the cylinder 41 is reduced. And the pressing force against the boom 2 decreases. In this case, when the rope tension T is sufficiently larger than the reference tension T0, the relief pressure continues to decrease and the relief pressure is kept at the minimum.

As described above, in the second embodiment, the rope tension T is controlled by controlling the relief pressure of the variable relief valve 42 according to the rope tension T and changing the pressing force from the backstop 19 to the boom 2. Since the reference tension T0 is maintained, the boom 2 is stably supported and the boom 2 can be prevented from swinging. In this case, since the reference tension T0 is increased as the boom 2 easily swings by the combination of the boom length and the jib length, the swing of the boom 2 is reliably prevented.

Third Embodiment A third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a hydraulic circuit diagram of a winch of a crane equipped with the safety device according to the third embodiment. The same portions as those in FIG. 5 are denoted by the same reference numerals, and the differences will be mainly described below. In FIG. 8, a goniometer 51 for detecting the elevation angle θ1 of the boom 2 is provided at the base end of the boom, and the goniometer 51 is connected to the controller 35.
In the second embodiment, the boom 2 is detected by the load detector 20.
Of the angle meter 5 in the third embodiment.
1 detects the ease of swinging of the boom 2 and controls the driving of the cylinder 41 according to the detection result. FIG.
In the figure, the moment limiter 36 is omitted.

FIG. 9 is a flowchart showing an example of processing executed by the controller 35 according to the third embodiment. This flowchart is started, for example, by turning on an engine key switch. First, step S
In step 21, the boom angle θ1 is detected based on the signal from the goniometer 51, and in step S22, the deviation A between the detected value θ1 and the previous boom angle detected value θ0 stored in the memory is calculated. Next, in step S23, it is determined whether or not the deviation A is larger than a preset reference value α. The reference value α in this case is a value for determining the presence or absence of the swing of the boom 2 and is determined in consideration of the resolution of the goniometer 51 and the like. If step S23 is affirmed, it is determined that the boom 2 has shaken, and the process proceeds to step S24. If step S23 is negative, the process skips step S24 and proceeds to step S25.
In step S24, a control signal for increasing the relief pressure of the variable relief valve 42 by a predetermined amount Δp is output, and the process proceeds to step S25. In step S25, the detected angle value θ
1 is stored as the previous value θ0 and the process returns.

In the third embodiment, when the swing of the boom 2 is detected based on the detection value from the goniometer 51, the pressure in the bottom chamber of the cylinder 41 is increased by the processing in the controller 35. As a result, the pressing force against the boom 2 increases, and the rope tension T increases, thereby preventing the boom 2 from swinging. In this case, it is not necessary to set conditions such as the reference tension T0 as shown in FIG. 6, and the pressing force against the boom 2 is increased only when the swing of the boom 2 is detected by the goniometer 51. Boom 2 depending on configuration
Is reliably prevented.

In the above description, the present invention is applied to the tower crane having the tower boom 2 and the jib 3.
It can also be applied to ordinary cranes without cranes. In the first embodiment, the pump tilt angle is controlled. However, the motors 23 and 24 are used as variable motors to control the tilt angle, and the pilots acting on the direction control valves 25 and 26 are controlled. The pressure may be controlled. In addition, boom 2
Although the drive speeds of both the boom 2 and the jib 3 are controlled, only the drive speed of the boom 2 may be controlled. Furthermore, although the characteristics of the pump tilt angle are different depending on the boom length and the jib length, the characteristics may be set in consideration of other parameters (for example, weight).

Further, in the first and second embodiments, the ease of swinging of the boom is detected by the rope tension T, and in the third embodiment, the boom 2 is determined by the amount of change in the boom angle θ1.
The swing of the boom 2 is detected by other physical quantities having a correlation with the swing of the boom 2,
Alternatively, the shaking may be detected. Further, in the second and third embodiments, the force acting on the boom 2 from the backstop 19 by driving the cylinder 41 is controlled, but the force acting on the boom 2 by something other than the cylinder 41 is controlled. You may make it control.

In the correspondence between the above-described embodiment and the claims, the load detector 20 and the goniometer 51 function as swing detecting means, the regulator 21 and the electromagnetic proportional valve 34 function as boom speed limiting means, and the controller 35 functions as control means. , Regulator 21
The electromagnetic proportional valve 34 constitutes the jib speed limiting means, the moment limiter 36 constitutes the identification means, and the hydraulic cylinder 41 and the variable relief valve 42 constitute the expansion and contraction means.

[0037]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first to fifth aspects of the invention, the boom undulation speed is limited according to the physical quantity having a correlation with the boom swing, so that the change in the moment load acting on the boom is reduced, The boom can be prevented from shaking. (2) According to the third aspect of the present invention, not only the boom but also the jib undulation speed is limited according to the physical quantity having a correlation with the boom sway, thereby preventing the boom sway due to the jib undulation. can do. (3) According to the fourth aspect of the invention, since the speed of the boom and the jib are limited by different characteristics, the swing of the boom can be efficiently prevented without restricting the hoisting speed more than necessary. . (4) According to the invention of claim 5, since the speed is limited by the characteristic based on the size of the boom and the jib, the influence on the boom swing caused by the difference in the boom length and the jib length is considered. , The speed limit is optimized. (5) According to the sixth and seventh aspects of the invention, the expansion and contraction of the backstop is controlled in accordance with the physical quantity having a correlation with the swing of the boom, so that the pressing force acting on the boom from the backstop increases. As a result, the boom is stably supported, and the boom is prevented from swinging. (6) According to the eighth and ninth aspects of the invention, the backstop is extended when the boom swing is detected by a physical quantity having a correlation with the boom swing, so that the boom is only moved when the boom swings. Pressing force is increased,
Shaking of the boom is reliably prevented.

[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 a hydraulic circuit diagram of the crane safety device according to the first embodiment.

FIG. 3 is a diagram showing a relationship between a rope tension and a target pump tilt angle.

FIG. 4 is a flowchart showing an example of processing in a controller constituting the safety device according to the first embodiment.

FIG. 5 is a hydraulic circuit diagram of a crane safety device according to a second embodiment.

FIG. 6 is a diagram showing the relationship between the ease of boom swing and the reference tension.

FIG. 7 is a flowchart illustrating an example of a process performed by a controller included in the safety device according to the second embodiment;

FIG. 8 is a hydraulic circuit diagram of a crane safety device according to a third embodiment.

FIG. 9 is a flowchart illustrating an example of a process performed by a controller included in the safety device according to the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Crane main body 2 Tower boom 3 Jib 8 Boom hoisting rope 19 Backstop 20 Load detector 21 Regulator 22 Hydraulic pump 34 Electromagnetic proportional pressure reducing valve 35 Controller 36 Moment limiter 41 Hydraulic cylinder 42 Variable relief valve 51 Angle meter

Claims (9)

[Claims] 1. A crane safety device comprising: a crane body; and a boom pivotally supported on the crane body, a swing detecting means for detecting a physical quantity having a correlation with the boom swing, and the boom. A safety device for a crane, comprising: a boom speed limiter configured to limit an up-and-down speed of the crane; and a controller configured to control the boom speed limiter in accordance with a physical quantity detected by the swing detection unit. 2. A crane safety device comprising: a crane body; a boom pivotally supported by the crane body; and a jib pivotally supported by a tip of the boom. Swing detection means for detecting a physical quantity having a correlation with the boom speed limiting means for limiting the boom undulation speed; control means for controlling the boom speed limiting means in accordance with the physical quantity detected by the swing detection means And a safety device for a crane. 3. The crane safety device according to claim 2, further comprising a jib hoisting speed limiting unit that limits the hoisting speed of the jib, wherein the control unit responds to a physical quantity detected by the shaking detecting unit. A crane safety device controlling the boom speed limiting means and controlling the jib speed limiting means. 4. The crane safety device according to claim 3, wherein the control means controls the boom speed control means and the jib speed control means with different characteristics. . 5. The safety device for a crane according to claim 2, further comprising identification means for identifying the size of the boom and the jib, and wherein the control means controls the size of the boom and the jib. A crane safety device for controlling the speed limiting means based on the speed. 6. A crane body, a boom pivotally supported by the crane body and a backstop provided between the back surface of the boom and the crane body to prevent the boom from tipping over. In the safety device for the crane, the swing detection unit that detects a physical quantity having a correlation with the swing of the boom, the extension and contraction unit that expands and contracts the backstop, and the extension and contraction unit according to the physical amount detected by the swing detection unit. A safety device for a crane, comprising: control means for controlling. 7. The crane safety device according to claim 6, wherein the swing detecting means comprises a tension detector for detecting a tension of a rope supporting the boom, and the control means comprises a tension detector by the tension detector. A safety device for a crane, wherein the extension / contraction means is controlled so that the detected rope tension becomes a predetermined value. 8. The crane safety device according to claim 6, wherein, when the swing detection unit detects the swing of the boom, the control unit controls the extendable unit to extend the backstop. A safety device for a crane, comprising: 9. The safety device for a crane according to claim 8, wherein the swing detecting means comprises an angle meter for detecting an elevation angle of the boom.