JP2000281284A - Overload preventing device for crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability and safety of a crane by lowering a derricking member to an erection quantity of the prescribed lower limit value or below without taking a release action when the derricking member is relatively short and no cargo is suspended. SOLUTION: The boom work radius R is calculated by the work radius computing unit 131 of an overload prevention section 13 based on the erection angle θ of a boom detected by a boom angle detector 5, and the maximum limit load Wa capable of being suspended in response to the boom erection angle θ is calculated by a limit load computing unit 132 based on the calculation result. The suspension load (actual load) W applied to the boom is calculated by a suspension load computing unit 133 from the guy cable tension F detected by a tension detector 12. A load factor W/Wa is calculated by a load factor computing unit 134 based on the calculated limit load Wa and suspension load W, and a warning is generated or boom erection drive is stopped based on the load factor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing overload of a crane, and more particularly, to an overload state in which an actual load acting on an undulating member mounted on a crane body so as to be able to undulate exceeds a set load. Therefore, the present invention relates to a crane overload prevention device in which the set load is set according to the amount of undulation of the undulating member in a range where the amount of undulation of the undulating member exceeds a predetermined lower limit.

[0002]

2. Description of the Related Art In a crane, since the load is hung on a lifting rope hung on an up-and-down member such as a boom or a jib mounted on the main body so as to be able to be raised and lowered, even if the same load is hung, When the undulation member is driven up and down to change the undulation angle of the undulation member, the main body may not be able to support the load and may fall down or the machine may be damaged. In order to prevent the above-mentioned overturn and damage to the machine, the undulation angle θ of the undulation member is often limited to a predetermined allowable operation range (upper limit θmax, lower limit θmin). Within this allowable operating range, the relief angle of the relief member theta (or working radius R is now operational) maximum limit load W _a which may be suspended in response to, for example, as shown in FIG. 5, the crane machine It is determined based on the target strength and the fall stability. For critical load W _a shown in FIG. 5, from the lower limit value θmin of the allowable operating range to the vicinity of the upper limit value θmax of the allowable operating range of the load W acting on the derricking angle θ and the relief member of the relief member product has been set the limit load W _a to be substantially constant, in the vicinity of the upper limit value θmax of the allowable operating range, set to a constant the critical load W _a substantially against derricking angle θ of the undulations member Have been. In the above crane, than limit load W _a as described above, to determine the overload condition actual load of the suspended load is large at the time of suspended load work, or give a warning to the driver or the like of the crane, the operation of the crane It is mandatory to install an overload prevention device that forcibly stops. The technology relating to such a crane overload prevention device is described in, for example, Japanese Patent Publication No. 3-27480. The lower limit value θmi of the undulation angle that determines the allowable operating range of the undulation member
In order to prevent damage to the hook hoisting rope, n is generally set to, for example, around an undulating angle of 30 ° at which the hook hoisting rope contacts the guide roller on the back of the boom. In the crane, in addition to the overload state, when the undulation angle θ of the undulating member reaches the lower limit θmin (up to 30 °), regardless of whether the load is suspended or not, The undulating drive is automatically or forcibly stopped by the overload prevention device. Therefore,
When the undulation member is lowered to the undulation angle equal to or less than the lower limit value θmin, it is necessary to cancel the automatic stop function of the undulation member by the overload prevention device. Release of the automatic stop function of the undulating member by the overload prevention device
For example, after the undulating member has been lowered to the lower limit value θmin and the undulating member has been temporarily stopped by the overload prevention device, the driver presses a release button for releasing the function, as shown in FIG. while only pressing a predetermined derricking angle theta _d min, it is performed by lowering the undulations member to the unactuated region where the auto-stop function does not work.

[0003]

By the above-described releasing operation, it is possible to lower the undulating member to an angle equal to or less than the lower limit value θmin. However, the undulating member is relatively short, and the load can be hung. Otherwise, the above-mentioned release operation is essentially unnecessary in terms of mechanical strength and fall stability. Since the release operation is performed simultaneously with the operation of lowering the undulating member, there is a possibility that the driver's attention to the operation of lowering the undulating member may be distracted even though the operation is originally unnecessary. . Also, if the release button is operated on a daily basis in order to lower the undulating member to the undulation angle equal to or less than the lower limit value θmin, the operation of the release button becomes habitual, and the luggage is hung. Therefore, even when it is necessary to prevent the overload state, the driver may accidentally press the release button. As described above, the conventional method of lowering the undulating member to the undulating angle equal to or less than the lower limit value θmin has problems in operability and safety. In order to solve such problems in the prior art, the present invention has improved an overload prevention device for a crane, and an actual load acting on an up-and-down member mounted on a crane body so as to be able to undulate exceeds a set load. To prevent load conditions
When the amount of undulation of the undulating member exceeds a predetermined lower limit,
In addition to setting the set load according to the amount of undulation of the undulating member, the range in which the amount of undulation of the undulating member exceeds the predetermined lower limit even when the amount of undulation of the undulating member is below the predetermined lower limit. By setting the set load at a value smaller than the minimum value in the above, if the luggage member is relatively short and the load is not hung, it is not necessary to perform the release operation, etc. It is an object of the present invention to provide a crane overload prevention device capable of lowering the amount of undulation below a predetermined lower limit.

[0004]

In order to achieve the above object, the invention according to claim 1 is directed to an overload state in which an actual load acting on an undulating member mounted on a crane body so as to be able to undulate exceeds a set load. In order to prevent this, in a crane overload prevention device in which the set load is set according to the amount of undulation of the undulating member within a range where the amount of undulation of the undulating member exceeds a predetermined lower limit, the set load is The amount of undulation of the undulating member is also set in a range below the predetermined lower limit, and the undulation of the undulating member is smaller than the minimum value of the set load in a range in which the amount of undulation exceeds the predetermined lower limit. It is configured as a crane overload prevention device characterized by being set as described above.

According to a second aspect of the present invention, in the crane overload prevention device according to the first aspect, the actual load exceeds the set load while the undulating member is driven up and down. The gist is that when the overload state is determined, the driving of the undulating member is automatically stopped.

According to a third aspect of the present invention, in the crane overload prevention device according to the second aspect, an up-and-down rope used for driving the up-and-down member to move up and down is stopped. I do.

According to a fourth aspect of the present invention, in the crane overload prevention device according to any one of the first to third aspects, the set load is the predetermined amount and the undulation amount of the undulating member is the predetermined amount. The gist is that the setting is made based on the load by the suspending means for suspending the luggage from the undulating member via the suspending rope within the range of the lower limit or less.

According to a fifth aspect of the present invention, in the crane overload prevention device according to any one of the first to fourth aspects, the amount of undulation is defined by the undulation angle of the undulation member,
Alternatively, the gist is a working radius of the undulating member calculated from the undulating angle of the undulating member.

According to the apparatus for preventing overload of a crane according to any one of claims 1 to 5, the overload that exceeds the set load when the actual load acting on the undulating member mounted on the crane body so as to be able to undulate is set. In order to prevent the state, the set load is set not only in accordance with the amount of undulation of the undulating member but also in the range where the amount of undulation of the undulating member exceeds a predetermined lower limit value. Is set to a value smaller than the minimum value in the range in which the undulating member is above the predetermined lower limit even in the range below the predetermined lower limit, the undulating member is relatively short and the load is hung. If it is not, the undulating member can be lowered to the undulation below the predetermined lower limit without the need to perform the above-mentioned release operation, etc., which is not necessary, thereby improving the operability and safety of the crane. Let it be Can.

According to another aspect of the present invention, an overload state in which the actual load exceeds the set load is determined while the undulating member is being driven up and down. If the driving of the undulating member is automatically stopped, the driver may erroneously lower the undulating member to an angle equal to or less than the predetermined lower limit even though the load is suspended. In this case, the up / down driving of the up / down member can be immediately stopped.

Here, the drive of the undulating member is stopped by stopping an undulating rope used for undulating the undulating member as in the overload protection device for a crane according to the third aspect of the present invention. It can be carried out.

The set load may be, for example, a crane overload prevention device according to the fourth aspect, in which the amount of undulation of the undulating member is less than or equal to the predetermined lower limit value. It is set based on the load by the suspending means for suspending the luggage via the lower rope.

The undulation amount is calculated from the undulation angle of the undulation member or the undulation angle of the undulation member, as in the crane overload prevention device according to the fifth aspect. This is the working radius of the member.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiments are specific examples of the present invention and do not limit the technical scope of the present invention. FIG. 1 is a view showing a schematic configuration of a crane overload prevention device according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining a schematic configuration example of a crane on which the above-mentioned overload prevention device is mounted. FIGS. 3 and 4 are flowcharts for explaining the operation of the crane overload prevention device, and FIG. 4 is a diagram for explaining the correspondence between the undulation angle of the undulating member and the limit load in the crane overload prevention device. It is. As shown in FIGS. 1 and 2, an overload prevention device for a crane according to an embodiment of the present invention includes a boom angle detector 5 for detecting an elevation angle θ of a boom (an example of an elevation member) 3, 3 based on a tension detector 12 for detecting a tension F of a guy cable 6C connected to the boom 3 and an elevation angle θ of the boom 3 detected by the boom angle detector 5.
A working radius calculator 131 for calculating the working radius of the boom 3, based on the working radius R of the boom 3 calculated by the working radius calculator 131, and the maximum limit load that can be suspended in accordance with the elevation angle θ of the boom 3. (set load) W load limit calculator 132 for calculating the _a, tension F Guy cables 6C which is connected to the boom 3 detected by the tension detector 12
Load (actual load) acting on the boom 3 based on the
Suspension load calculator 133 calculates the W, the limit load above limit load calculated by the calculator 132 W _a, and the suspension load W calculated by the suspension load calculator 133
And an overload prevention unit 13 including a load ratio calculator 134 for calculating a load ratio that is _a ratio W / Wa of the two, and an alarm based on the load ratio output from the overload prevention unit 13. An alarm / operation automatic stop device 14 that emits and automatically stops the up / down driving of the boom 3 is provided. The configuration of the crane overload prevention device according to the present embodiment is the same as that of the conventional device.
Setting of the limit load W _a to be used in 2, in the conventional apparatus, while being conducted only between the upper limit value θmax and the lower limit value θmin as shown in FIG. 5, the present embodiment according overload preventing apparatus for a crane, as shown in FIG. 4, the minimum limit load Wmin in the range are the lower limit θmin the critical load W _a even less setting, and that the relief angle θ is larger than the lower limit value θmin The difference is that the value is set to a smaller value.

Hereinafter, the crane overload prevention device according to the present embodiment will be described in detail. First, the crane 1 main body on which the overload prevention device including the boom angle detector 5, the tension detector 12, the overload prevention unit 13, and the alarm / operation automatic stop device 14 is mounted has a boom pin 2 and a boom 3 as a center. Are mounted so as to be able to be raised and lowered, and a winch drum 4A for hanging a load and a winch drum 4B for raising and lowering a boom are provided. A rope (suspension rope) 6A pulled out from the winch drum 4A is hung on a sheave 7 of a boom head (boom tip), and the rope 6A causes a hook block 8 (an example of suspension means).
Is suspended. A rope (up-and-down rope) 6B pulled out from the winch drum 4B is wound between a pair of moving pulleys 9A and 9B. One of the moving pulleys 9A is rotatable via a pin 11 on the crane 1 body side. Support member 1
a, and the other moving pulley 6B is connected to the boom head via a guy cable 6C. That is, the hook block 8 is raised and lowered by the rotation of the winch drum 4A, and the boom 3 is raised and lowered by the rotation of the winch drum 4B. The hydraulic circuit configuration of the winch drum hoisting control device may be the same as that of a well-known hydraulic circuit. For example, see JP-A-7-41287. And the boom angle detector 5 of the overload prevention device is provided at the base of the boom 3,
The tension detector 12 of the overload prevention device is provided between the moving pulley 9A and the support member 1a on the crane 1 body side. In addition, the overload prevention unit 13 and the alarm / operation stop device 1
4 is installed in the cab of the main body of the crane 1 and is electrically connected to the boom angle detector 5 and the tension detector 12.

Next, referring to the flowchart of FIG.
The operation of the crane overload prevention device will be described. First, a detection signal is read from the boom angle detector 5 to the overload prevention unit 13 (S101), and the undulation angle θ of the boom 3 is in a range exceeding a predetermined lower limit value θmin or is equal to or smaller than the lower limit value θmin. It is determined whether it is within the range (S102). In the step S102, when it is determined that the undulation angle θ of the boom 3 is in a range exceeding the lower limit value θmin, the overload prevention unit 13
The working radius R of the boom 3 at that time is calculated by the working radius calculator 131 based on the undulation angle θ of the boom 3 and the length of the boom 3, and the limit load calculation of the overload prevention unit 13 is performed. The working radius R is determined by the
Critical load W _a is calculated based on (S103).

[0017] In the limit load calculator 132, for example, the operating radius R of the boom 3, as shown in FIG. 4 (or derricking angle theta), correspondence between the critical load W _a are held in advance, the work When the radius R is supplied to the critical load calculator 132 from the working calculator 131, the corresponding relationship is referred by the limit load calculator 132, the critical load W _a is calculated. Incidentally, the critical load W _a refers to the maximum load that can be suspended in accordance with the derricking angle of the boom 3 theta, which is an example of a set load of the present invention,
For example, instead of the limit load W _a, it may be used rated load W ₀ which is set slightly smaller than the critical load W _a in consideration of the safety factor. In the correspondence shown in FIG. 4, the upper limit value Rma of the allowable operation range of the boom 3 is set.
Between x (θmax) and the lower limit value Rmin (θmin), the above-mentioned rated total load W ₀ is used. Further, in this between the upper limit value Rmax and the lower limit value Rmin, as in the conventional device, the rated load W ₀ so that the product is substantially constant between the working radius R and the load W is set. In this case, the rated total load W ₀ becomes minimum at the lower limit value Rmin,
The value at that time is Wmin.

[0018] limit load W _a (or rated load W ₀₎ as described above is calculated, then the tension detector 1
2, the tension detection signal of the guy cable 6C detected by the cable 2C is read out by the overload state unit 13, and the suspension load calculator 133 applies a suspension load acting on the boom 3 based on the read tension detection signal. W is calculated (S104). Next, the above limit load W _a computed in the step S103, and the above suspension load W which is computed in the step S104, the limit load calculator 13
2. From the hanging load calculator 133 to the load factor calculator 1
34 are supplied, a both the ratio W / W _a load ratio is calculated by the load factor calculator 134 (S10
5). When the load factor is calculated by the load factor calculator 134, the overload prevention unit 13 determines whether the load factor is 90% or less, in the range of 90% to 100%, or 100%. It is determined whether this is the case (S106). In the step S106, when the load factor is to distinguish between 90% or less has been performed, it means that the critical load W _a from the suspension load W is less 10% or more, falling and breakage of the machine or the like There is no danger of the above-mentioned step S101
The processing is returned to. In the above step S106,
If the judgment of the load factor is in a range of 90% to 100% is by the overload prevention unit 13, the suspension load W is a value close to the critical load W _a, undulations in this state the boom 3 When driven, since the suspension load W is high may become overloaded reached the critical load W _a, notice sound indicating to that effect is issued from the alarm-deactivation device 14 (S107), thereafter the processing is the The process returns to step S101. In the step S106, the overload prevention unit 13 determines that the load factor is 100% or more.
If done by, the suspension load W has already exceeded the limit load W _a, or cause the overturning of the crane 1 body when left alone, because it may be damaged machines, alarm indicating that fact Or a synthesized voice is issued from the alarm / operation stopping device 14, and the unwinding of the winch drum 4B, that is, the rope 6B is immediately stopped based on a control signal from the alarm / operation stopping device 14, The up / down driving of the boom 3 is forcibly or automatically stopped (S108), and the process is thereafter returned to the step S1. Such steps S101 to S101
The operation of the crane overload device represented by 108 is similar to that of the conventional device.

On the other hand, in the step S102, the block
Angle 3 of the arm 3 is in the range below the lower limit value θmin.
If it is determined that the lifting load is
Luggage is not suspended regardless of the size of W
Even in this case, the processing is moved to the step S108,
・ Alarm, operation stop, etc. are performed by the operation stop device 14.
In contrast, the crane according to the present embodiment
In the stopping device, as shown in FIG.
2 and the working radius R (or undulation angle θ)
The correspondence between the load W and the upper limit value Rmax and the lower limit value
Rmin as well as the range below the lower limit Rmin
However, the lower limit value Rmin (or θmin
 ) Even in the following cases, the above steps S103 to S
The processing of 108 is performed. That is, in the above step S102,
And the up-and-down angle θ of the boom 3 is smaller than the lower limit value θmin.
It is determined by the overload prevention unit 13 that it is in the lower range.
If this is done, prevent the crane according to this embodiment from overloading.
In the device, the work radius calculator 131 performs the work half operation.
The diameter R is calculated, and the limit load calculator 132 calculates the diameter R.
Critical load W _aIs calculated. The lifting load at that time
W is calculated by the hanging load calculator 133, and
The load factor is calculated by the load factor calculator 134,
A determination is made for the load factor.

Here, in the relationship between the working radius R (or the undulation angle θ) and the load W held in the limit load calculator 132, the limit load W is not more than the lower limit value Rmin (θmin). _a is set at a value smaller than the minimum value Wmin of the rated load W _0. The upper limit R
critical load W _a of the working tolerance, or rated load W ₀ is luggage has suspended, considering that the maximum capacity of the crane is required set between max and the lower limit value Rmin while being, critical load W _a in the range of the lower limit value Rmin are set on the assumption that the package is not suspended. Critical load W _a in the range of the lower limit Rmin, for example based on the tension detection signal of the tension detector 12 when the weight of the hook block 8, or the luggage to the hook block 8 not suspended This is a substantially constant value smaller than the minimum value Wmin of the determined total rated load Wa, and is _a minimum necessary value for suspending the hook block 8 on which no load is suspended. Therefore, the above work tolerance, in the range of less than the lower limit value Rmin, the critical load W _a is discontinuous. Therefore, even if the driver attempts to lower the boom 3 to a range equal to or less than the lower limit value Rmin when the luggage is not suspended on the hook block 8, if the luggage is not suspended, Suspension load W
But it does not exceed the critical load W _a, although there is a case where the notice sound or the like is emitted, without operating the release button, etc. as in the conventional apparatus, it is possible to continue the descent of the boom 3. On the other hand, if the driver mistakenly attempts to lower the boom 3 to a range equal to or less than the lower limit value Rmin even though the load is hung on the hook block 8, the lower limit value Rmin is reached. although up is possible drop of the boom 3, for the critical load W _a decrease discontinuously increased in the lower limit Rmin, the load factor above suspension load W is greater than the critical load W _a 100 %, The alarm / operation stop device 14 issues an alarm, and the rope 6B, that is, the up / down driving of the boom 3 is immediately stopped.

As described above, according to the crane overload prevention device according to the present embodiment, it is necessary to prevent an overload state in which the suspension load acting on the boom mounted on the crane body so as to be able to undulate exceeds the limit load. The limit load is set not only in accordance with the boom angle or working radius but also in the range where the hoisting angle or working radius of the hoisting member exceeds a predetermined lower limit. Even when the radius is less than or equal to the predetermined lower limit, the boom is set to a value smaller than the minimum value in the range where the boom undulation angle or the working radius is greater than the predetermined lower limit. If the boom has not been lowered, the boom can be lowered to an angle equal to or less than the predetermined lower limit without the necessity of performing the above-described releasing operation and the like which are not originally required. It is possible to improve the operability and safety of the lane. In the above-described embodiment, a single boom is described as an example of the undulating member in the present invention. However, the present invention is not limited to this. A member including a plurality of booms and jib is also a specific example of the undulating member. is there. The crane to which the present invention is applied is, for example, a crawler crane. However, the present invention is not limited to this. Applicable.

[0022]

As described above, according to the apparatus for preventing overload of a crane according to any one of claims 1 to 5, the actual load acting on the undulating member movably mounted on the crane body. In order to prevent an overload condition that exceeds the set load, the set load is set not only in accordance with the amount of undulation of the undulating member in a range where the undulation of the undulating member exceeds a predetermined lower limit value. Even when the amount of undulation of the undulating member is equal to or less than the predetermined lower limit, the amount of undulation of the undulating member is set to a value smaller than the minimum value in a range exceeding the predetermined lower limit. When the load is not suspended for a relatively short time, the undulating member can be lowered to the undulation amount below the predetermined lower limit without performing the releasing operation or the like that is not originally required, and as a result, the crane Operability and It is possible to improve the total resistance. Further, when an overload state in which the actual load exceeds the set load is determined while the up-and-down member is being driven up and down, as in the overload device for a crane according to claim 2,
If the driving of the undulating member is automatically stopped, the driver may erroneously try to lower the undulating member to an angle equal to or less than the predetermined lower limit, even though the load is suspended. Also, it is possible to immediately stop the undulating drive of the undulating member. Further, according to the overload device for a crane according to the fourth aspect, the set load is set such that the amount of undulation of the undulating member is equal to or less than the predetermined lower limit value and the undulating member is connected to the undulating member via a suspension rope. Since the setting is made based on the load by the suspending means for suspending the load, when the undulating member is to be lowered to the amount of undulation below the predetermined lower limit, the load is suspended by the suspending means. It can be automatically determined whether or not the operation has been performed.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a schematic configuration of a crane overload prevention device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration example of a crane on which the overload prevention device is mounted.

FIG. 3 is a flowchart for explaining the operation of the overload prevention device.

FIG. 4 is a view for explaining a correspondence relationship between a hanging load and a working radius in the overload prevention device.

FIG. 5 is a diagram for explaining a correspondence relationship between a hanging load and a working radius in a conventional crane overload prevention device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Crane 3 ... Boom 4A, 4B ... Winch 5 ... Boom angle detector 6A, 6C ... Rope 8 ... Hook block 12 ... Tension detector 13 ... Overload prevention part 14 ... Alarm / operation stop device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F204 AA04 BA02 CA05 FA02 FB19 FC01 FC05 FC08 FD02 FD06 3F205 AA07 CA01 CA09 DA02 HA02 HA06 HB01 HB02 HB04 HC01 HC04 KA10

Claims (5)

[Claims] In order to prevent an overload state in which an actual load acting on an up-and-down member mounted on a crane body so as to be able to undulate exceeds a set load, the up-and-down amount of the up-and-down member exceeds a predetermined lower limit value. In the crane overload prevention device in which the set load is set according to the amount of undulation of the undulating member, the set load is set even in a range where the amount of undulation of the undulating member is equal to or less than the predetermined lower limit. And an overload prevention device for a crane, wherein the amount of undulation of the undulating member is set to be smaller than a minimum value of the set load in a range exceeding the predetermined lower limit value. 2. When the overload state in which the actual load exceeds the set load is determined while the up / down member is being driven up / down, the driving of the up / down member is automatically stopped. Item 2. The crane overload prevention device according to Item 1. 3. The overload protection device for a crane according to claim 2, wherein an up-and-down rope used for driving up and down the up-and-down member is stopped. 4. The set load is based on a load by a suspending means for suspending a load from the up-and-down member via a suspension rope when the amount of up-and-down of the up-and-down member is within the predetermined lower limit. The crane overload prevention device according to any one of claims 1 to 3, wherein the crane overload prevention device is set. 5. The crane according to claim 1, wherein the amount of undulation is a undulation angle of the undulation member or a working radius of the undulation member calculated from the undulation angle of the undulation member. Overload protection device.