JP3402292B2 - Crane overload protection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a crane overload preventing device for preventing a crane from being damaged or falling during a hanging operation.

[0002]

2. Description of the Related Art A crane is equipped with an overload prevention device for the purpose of preventing damage and tipping over, and is equipped with a controller which is a calculation means for calculating the load of a suspended load. As a crane overload prevention device, one disclosed in, for example, Japanese Patent Application Laid-Open No. 7-172776 is known. The outline of the overload prevention device (operation control device) according to this conventional example will be described below.

This overload prevention device (operation control device)
Whether the operation of the boom etc. is actually stopped while the operation of the boom etc. is automatically stopped by activating the operation stop means based on the stop signal. In addition, the malfunction is detected when the malfunction occurs, and the malfunction is notified to the operator to improve the reliability of the overload prevention device.

More specifically, when a stop signal is output from the controller of the overload prevention device, an electric output signal is sent to determine whether or not the stop signal reliably acts on an actuator such as a hydraulic cylinder or hydraulic motor. When the output from the controller of the overload prevention device and the output of the actuator do not match due to detection or hydraulic pressure detection, an abnormal alarm is issued from the alarm generation means to cause malfunction of the operation stop means to the operator. It is intended to inform.

[0005]

According to the overload prevention device (operation control device) according to the above-mentioned conventional example, when the operation of the boom or the like cannot be stopped due to a malfunction of the operation stopping means, an alarm is issued. Informs the operator that the deactivation means is abnormal. However, this does not prevent the abnormal state, but merely entrusts the operator to get out of the dangerous state. That is,
In order to ensure true safety, it is preferable that the overload prevention device has a function capable of automatically avoiding an abnormal state of the operation stopping means. In addition, because a separate sensor is provided to detect abnormalities from the output from this sensor and to judge abnormalities by position changes to the dangerous side, it is not always sufficient in terms of reliability and responsiveness. It was something I couldn't say.

Therefore, it is an object of the present invention to, when an abnormality occurs in the automatic stop output output means, immediately avoid the abnormality and guarantee a normal output to ensure the operation of the crane equipment. It is an object of the present invention to provide a crane overload prevention device which can be stopped and has excellent reliability and responsiveness.

[0007]

In order to solve the above-mentioned problems, the means adopted by the crane overload prevention device according to claim 1 of the present invention is characterized in that the load of the suspended load obtained by calculation is Is compared with the rated load, it is determined that the load of the suspended load is heavier than the rated load and the crane may tip over, and a calculation means for outputting a stop command for stopping the automatic stop operation part is provided. In an overload prevention device for a crane, which is provided with an operation output output means for receiving an operation output for stopping the automatic stop operation part, an output switching means is interposed between the computing means and the operation output output means. , Sub-operation output output means for receiving a stop command via the output switching means to operate the sub-automatic stop operation part,
The stop command output from the calculation means and the operation output output from the operation output output means are compared with each other, and if they do not match, it is determined that the operation output is abnormal, and the output switching means is operated from the operation output output means side to the auxiliary side. The output abnormality detecting means for switching and operating the operation output outputting means is provided.

The stop command output from the calculation means of the overload prevention device is caused by a malfunction of the operation output means, disconnection of wiring or short circuit with earth, contact with other lines, electromagnetic switching valve, electromagnetic proportional valve, etc. There is no meaning unless the electromagnetic switching valve or the electromagnetic proportional valve normally operates due to a malfunction such as a solenoid malfunction. However, according to the crane overload prevention device of the first aspect, even if the automatic output stop means cannot operate due to an abnormality in the operation output output means, the output switching means causes the operation output output means to operate. Is switched to the side of the sub-actuation output output means, and the sub-actuation stop output is operated by the sub-actuation output output from the sub-action output output means, so that the overload prevention device normally functions.

The feature of the means adopted by the crane overload prevention device according to claim 2 of the present invention is that the load of the suspended load is calculated by comparing the load of the suspended load obtained by calculation with the rated load. It is determined that the crane is likely to tip over and is heavier than the load, and equipped with a computing unit that outputs a stop command to stop the automatic stop operation unit, and outputs an operation output that receives the stop command and stops the automatic stop operation unit. In a crane overload prevention device including operation output output means, a sub-operation in which an output switching means is interposed between the computing means and the operation output output means, and a stop command is received via the output switching means. The output output means is provided, and the stop command output from the calculation means and the operation output output from the operation output output means are compared. If they do not match, it is determined that the operation output is abnormal, and the output switching means Is provided from the operation output output means side to the sub-operation output output means side, and the output abnormality detecting means is provided to operate the output abnormality output means. The second output switching means for receiving the normal operation output and operating the automatic stop operation portion is provided.

According to the crane overload prevention device of the second aspect, even if the automatic output stop means cannot operate due to an abnormality in the operation output output means, the output switching means causes the operation output output means to operate. Side is switched to the sub-operation output output means side, and the sub-operation output output from the sub-operation output output means is operated through the second output switching means, so that the automatic stop actuation section is actuated. Works fine.

The means adopted by the crane overload prevention device according to claim 3 of the present invention is characterized in that the crane overload prevention device according to any one of claims 1 and 2 is characterized. In the above, the stop command output from the computing means is compared with the sub-operation output output from the sub-operation output output means, and if they do not match, it is determined that the sub-operation output is abnormal, and the output switching means is turned on. An auxiliary output abnormality detecting means for switching the auxiliary operation output output means side to another auxiliary operation output output means side is provided.

According to the crane overload prevention apparatus of the third aspect, in addition to the operation of the crane overload prevention apparatus of the first or second aspect, the auxiliary output abnormality detection means is used to provide the auxiliary operation output output means. By knowing the abnormality of, the abnormality of the auxiliary operation output line can be automatically avoided.

The feature of the means adopted by the crane overload prevention device according to claim 4 of the present invention is that the crane overload according to any one of claims 1, 2 or 3 is characterized. In the prevention device, the output of the calculation means is set to O
In order to recognize the timing at which an abnormality in the operation output output means or the auxiliary operation output output means can be detected before performing crane work by switching to both the N state and the OFF state,
There is provided a power supply rise determination means for determining the rise of the computing means.

A feature of the means adopted by the crane overload prevention device according to claim 5 of the present invention is that the crane overload according to any one of claims 1, 2 and 3 is characterized. In the prevention device, the output of the calculation means is set to O
In order to recognize the timing at which an abnormality in the operation output output means or the auxiliary operation output output means can be detected before performing crane work by switching to both the N state and the OFF state,
The operation means is provided with crane operation state detection means for detecting the operation state of the crane and determining the crane operation state.

According to the crane overload prevention device of the fourth or fifth aspect, the crane is operated by the power supply rise determination means for determining the rise of the computing means and the crane operation state detection means for detecting the crane operation state. You can know when the crane work cannot be done although you are in a state of gaining money. In other words, when the crane work is not possible, that is, when there is no need for automatic stop, it is possible to know the abnormality of the operation output output means or the auxiliary operation output output means, and to utilize the normal operation output output means before the crane operation. It is possible to prevent the crane from tipping over or being damaged in advance.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The construction of an overload preventing device for a crane according to Embodiment 1 corresponding to claim 1 of the present invention will be described below with reference to FIG. 1 (side view of a crane equipped with this overload preventing device). a) and FIG. 1 of the schematic configuration diagram of the overload prevention device
FIG. 2B is a block diagram of (b) and its automatic stopping means.
(A), (b) and FIG. 3 of the configuration explanatory view of the output switching means
The description will be made with reference to (a) and (b) and FIGS. 4 (a) and 4 (b) of the configuration explanatory diagram of the operation output output means in order.

First, the construction of a crane equipped with an overload prevention device will be described with reference to FIGS. 1 (a) and 1 (b), taking the case where the crane is a crawler crane as an example.
Reference numeral 1 denotes a crawler traveling type lower traveling body, and on the lower traveling body 1, a rotatable upper revolving body 2 having a lattice-type boom 3 capable of undulating at a front portion is mounted. An upper spreader 6 is connected to the other end of a guy cable 5 whose one end is connected to the vicinity of the upper part of the boom 3, and the upper spreader 6 and the triangular shape provided on the upper part of the rear part of the upper revolving structure 2 are connected. Between a plurality of sheaves (not shown) connected to the lower spreader 7 connected to the top of the gantry 4 and a boom hoisting rope 9 that is wound and unwound by a boom hoisting drum 8 provided on the upper revolving structure 2. It has been forgotten. In other words, the boom 3 has the boom hoisting rope 9
The upper and lower spreaders 6 and 7 whose intervals are expanded and contracted by winding and unwinding are wound up and down via the guy cable 5.

A guide sheave 3a and a top sheave 3b are provided at the tip of the boom 3, and the sheaves 3a and 3b are wound by a hoisting drum 11 provided on the upper revolving structure 2 and unwound. A hoisting rope 10 is suspended. The hoisting rope 10 hooked on one of the sheaves of the top sheave 3b and turned downward is a plurality of sheaves of the top sheave 3b and a plurality of sheaves of the hooks 12 for suspending suspended loads. The tip end of the hoisting rope 10 which is hung up between the hook 12 and one of the sheaves of the hook 12 and is turned upward by one of the sheaves is connected to a lower position of the point sheave 32 of the boom 3. The hook 12 is configured to be raised and lowered by winding and unwinding the hoisting rope 10.

In the crane having such a construction, the boom spreader 21 for detecting the hoisting angle of the boom 3 and the lower spreader for finding the boom hoisting force F by detecting the tension of the boom hoisting rope 9 for hoisting the boom 3 are obtained. 7, a calculation means for calculating a load factor (load / rated load) or the like from a load meter 22 attached to the boom angle meter 21, a boom angle θb input from the boom angle meter 21 and a boom hoisting force F input from the load meter 22. The overload prevention device 20 including the controller 23 is provided.

The overload prevention device 20 has an arithmetic expression for calculating the weight component of the boom or the weight component of the boom 3.
The rated load WR for the working radius calculated from the boom angle θb and the boom length is set. Then, a load W _A1 of the suspended load from the boom hoisting force F inputted from the load meter 22 and calculates the weight component of the boom 3, the obtained load W _A1 of the suspended load is more than rated load W _R of the suspended load Then, a warning is issued that the crane may be damaged or fall over, and, for example, an electromagnetic switching valve that is an automatic stop operating unit that controls the rotation of a hydraulic motor that rotates the boom hoisting drum 8 that hoists the boom 3. By supplying an excitation voltage to the (solenoid), a stop command for operating the spool of the electromagnetic switching valve to stop the rotation of the hydraulic motor is output. In the first embodiment, however, such a general stop command is output. The overload prevention device 20 having a configuration is provided with an automatic stop unit 30 having a configuration described later. The tension T of the hoisting rope 10 is calculated in order to calculate the load W _A1 of the suspended load.
May also be entered.

The structure of the automatic stop means 30 will be described below with reference to FIGS. 2 (a), 3 (a), 3 (b), 4 (a) and 4 (b). An output switching means 31, which will be described later, for receiving the stop command is provided. An operation output output, which will be described later, receives a stop command output from the controller 23 via the output switching means 31 and outputs an excitation voltage which is an operation output to the solenoid 13 of the electromagnetic switching valve which is the automatic stop operation portion. Means 32 (hereinafter referred to as main output means) are provided.
Further, the sub-solenoid 1 of the electromagnetic switching valve, which is the sub-automatic stop actuating section, receives the stop command via the output switching means 31.
4 is provided with a sub-operation output output means 34 (hereinafter, referred to as a sub-output means) which outputs an exciting voltage to the motor 4.

Further, the stop command output from the controller 23 is compared with the excitation voltage output from the main output means 32, and if they do not match, the main output means 32 is used.
There is provided an output abnormality detecting means 33 for deciding that the output is abnormal and switching the output switching means 31 from the normal main output means 32 side to the sub output means 34 side. That is, when an abnormality occurs in the main output means 32, the auxiliary solenoid 14 is excited via the auxiliary output means 34 to operate the spool of the electromagnetic switching valve to stop the rotation of the hydraulic motor. As a result, the operation of the crane operation system is stopped, resulting in a two-system fail-safe configuration.

As shown in FIG. 3A, the output switching means 31 has a relay 31a which is excited by the input of an abnormality signal from the output abnormality detecting means 33 and a contact point 31b which is switched by the operation of the relay 31a. And a main contact 31c on the main output means 32 side and a sub-contact 31d on the sub output means 34 side. Also, FIG.
It is possible to use a non-contact type structure as shown by a logic symbol in (b), and this non-contact type one is preferable in consideration of life and the like.

Since the main output means 32 and the sub-output means 34 have the same construction, the construction will be described by taking the main output means 32 as an example, which is constructed as shown in FIG. 4 (a). . That is, this is an electric circuit, and includes an output power cord 32a, a relay 32b connected when receiving a stop command output from the controller 23 via the output switching means 31, and an electric circuit protection circuit. A fuse 32d is interposed and is composed of an output cord 32c connecting the relay 32a and the solenoid 13 of the electromagnetic switching valve. Further, as shown in FIG. 4B, when the excitation voltage is output by the stop command, the output transistor 3 is used.
2e is operated to supply the exciting voltage to the solenoid 13 of the solenoid operated directional control valve, the overcurrent detection resistor 32f is provided to protect the electric circuit due to the overcurrent, and the overcurrent detection resistor 32f is used. An overcurrent protection circuit 32g for turning off the operation command of the output transistor 32e when a current is detected may be provided.

In the first embodiment, as described above, normally, the main output means 32 excites the solenoid 13, and when the main output means 32 becomes abnormal, the sub output means 34 causes the sub solenoid. It is configured to excite 14. The solenoid 13 and the sub solenoid 14
The solenoid 13 and the sub-solenoid 14 may be provided in one electromagnetic switching valve. For example, when the solenoid 13 and the sub-solenoid 14 are provided in one electromagnetic switching valve, they are provided in duplicate on one side of one spool, in series on one side of one spool, or on both sides. The configuration may be changed.

By the way, the operation unit of the controller 23 may be configured to switch the stop command. However, if the output switching means 31 is a hardware configuration independent of the controller 23 and dedicated to the switching, the responsiveness is excellent and
This is because the structure is simplified and it is possible to contribute to the improvement of its reliability. Further, although the arithmetic unit of the controller 23 can be utilized to detect an abnormality of the main output means 32, as in the case of the output switching means 31, the output abnormality detection means 33 has an independent hardware configuration. Is excellent in responsiveness and simplifies the configuration, which can contribute to improvement in reliability. The output abnormality detecting means 33 may use a comparator or the like. Of course, it does not necessarily depend on an independent hardware configuration.

The overload prevention device 20 having the above structure will be described below.
The operation mode of the automatic stop means 30 will be described. When the stop command is output from the controller 23, the main output means 3
When abnormality occurs in 2, the solenoid 13 cannot be excited. However, when the abnormality of the main output means 32 is detected by the output abnormality detecting means 33,
The output switching means 31 operated by the output of the output abnormality detecting means 33 moves from the main output means 32 side to the sub output means 34.
The auxiliary solenoid 14 is excited by the auxiliary excitation voltage output from the auxiliary output means 34. As a result, the electromagnetic switching valve is operated, so that, for example, the rotation of the hydraulic motor that rotates the boom hoisting drum 8 that hoists the boom 3 is stopped. That is, even if an abnormality occurs in the main output means 32, the overload prevention device 20
Will function normally.

According to the overload prevention device of the first embodiment, when the operation stopping means malfunctions and the operation of the boom or the like is no longer stopped, an alarm informs that the operation stopping means is abnormal. Unlike the overload prevention device (operation control device) according to the conventional example that informs the operator, as described above, the abnormal state is automatically restored to the normal state by the action of the output switching means 31. Reliably avoiding the risk of tipping or failure can greatly contribute to improving safety in crane work. Further, as described above, the output switching means 31 and the output abnormality detecting means 33 have a dedicated hardware configuration different from that of the controller 23 and are excellent in responsiveness and reliability, so that the danger is quick and reliable. There is an excellent effect that can be avoided. Of course, it does not necessarily depend on an independent hardware configuration.

By the way, in the first embodiment, as shown in FIG. 2B, the excitation result of the solenoid 13 may be fed back to the output abnormality detecting means 33. Automatic stop means 30 of this overload prevention device
The configuration of (1) is applied to an electromagnetic proportional valve having a solenoid that is excited by an exciting current.

Second Embodiment Corresponding to Claim 2 of the Present Invention
Regarding the configuration of the automatic stop means 30 of the overload prevention device according to the present invention, the same components as those in the first embodiment and components having the same functions are designated by the same reference numerals with reference to FIG. 5A of the block diagram. A configuration different from that of the first embodiment will be described, as will be well understood in a comparison between FIG. 2A according to the first embodiment and FIG. 5A according to the second embodiment. , Operates in conjunction with the output switching means 31,
A second output switching means 31 'for operating the solenoid 13 by receiving a normal excitation voltage output from the main output means 32 or the sub output means 34 is provided.

According to the automatic stop means 30 of the overload prevention apparatus according to the second embodiment, when the output abnormality detecting means 33 detects that the output means 32 is abnormal, the output switching means 31 and the The two-output switching means 31 'is switched from the main output means 32 side to the sub output means 34 side. Then, the solenoid 13 is excited by the excitation voltage output from the sub-output means 34 and the electromagnetic switching valve is operated, so that the rotation of the hydraulic motor for rotating the boom hoisting drum 8 for hoisting the boom 3 is stopped, and Main output means 3
Since the overload prevention device 20 functions normally even if the abnormality occurs in item 2, the second embodiment has the same effect as that of the first embodiment when the solenoid 13 functions normally.

In the second embodiment, as shown in FIG. 5B, the excitation result of the solenoid 13 may be fed back to the output abnormality detecting means 33. The structure of the automatic stop means 30 of this overload prevention device is as follows.
Similar to the case of the first embodiment shown in FIG. 2B, the present invention is applied to an electromagnetic proportional valve having a solenoid that is excited by an exciting current.

Embodiment 3 corresponding to claim 3 of the present invention
Regarding the configuration of the automatic stop means 30 of the overload prevention device according to the present invention, referring to FIG. 6 (a) of the block diagram, the same components as those in the first embodiment and components having the same functions are designated by the same reference numerals. A configuration different from that of the first embodiment will be described, as will be well understood in a comparison between FIG. 2A according to the first embodiment and FIG. 6A according to the second embodiment. In addition to the output abnormality detecting means 33 for detecting an abnormality of the main output means 32, the stop command output from the controller 23 is compared with the sub-excitation voltage output from the sub-output means 34. It is determined that the normal sub-excitation voltage is not output because the sub-output means 34 is abnormal, and the sub-output for switching the output switching means 31 ″ from the sub-output means 34 side to another sub-output means side (not shown) is operated. The abnormality detection means 35 It is obtained by the only configuration.

According to the automatic stop means 30 of the overload prevention device according to the third embodiment, in addition to the effect of the first embodiment, the abnormality of the auxiliary output means 34 is detected by the auxiliary output abnormality detecting means 35. It is possible to know that, for example, by providing a plurality of sub-output means, it is possible to switch to another normal sub-output means in order to exert the automatic stop function, or to prevent an overload by notifying the abnormality of the sub-output means. Since the repair of the device will be prompted, it is possible to cope with the perfection of the automatic stop function. Incidentally, if the abnormality of the sub-output unit 34 cannot be known even though the main output unit 32 is switched to the sub-output unit 34 due to the abnormality, the crane operation is performed without the operator noticing the abnormality. This is extremely dangerous. It should be noted that the output switching means 31 ″ has a slightly different function from the output switching means 31 according to the first embodiment in that a plurality of sub output means are sequentially switched to other normal sub output means. is there.

In the third embodiment, as shown in FIG. 6B, the result of the excitation of the solenoid 13 is output to the output abnormality detecting means 33, and the result of the excitation of the sub-solenoid 14 is the output abnormality detecting means 35. It can be configured to feed back to each. Automatic stop means 3 of this overload prevention device
The configuration of 0 is applied to an electromagnetic proportional valve having a solenoid that is excited by an exciting current, as in the case of the first embodiment shown in FIG. 2B.

Embodiment 4 corresponding to claim 3 of the present invention
Regarding the configuration of the automatic stop means 30 of the overload prevention device according to the present invention, the same components as those in the second embodiment and components having the same functions are designated by the same reference numerals with reference to FIG. 7A of the block diagram. A structure different from that of the second embodiment will be described, as will be better understood by comparing FIG. 5A according to the second embodiment and FIG. 7A according to the fourth embodiment. Similarly to the third embodiment, the auxiliary output abnormality detecting means 35 for detecting an abnormality of the auxiliary output means 34 is provided, and more specifically, a stop command output from the controller 23 and an output from the auxiliary output means 34 are output. The sub-output means 34
Is abnormal, it is judged that the normal auxiliary excitation voltage is not output, and the auxiliary output abnormality detecting means 35 for switching the output switching means 31 ″ from the auxiliary output means 34 side to another auxiliary output means side (not shown) is operated. Is provided.

Therefore, according to the automatic stop means 30 of the overload prevention device according to the fourth embodiment, the abnormality of the auxiliary output means 34 can be detected by the auxiliary output abnormality detecting means 35 as in the case of the third embodiment. Therefore, when a plurality of sub-output means are provided, it is possible to sequentially switch to another normal sub-output means so that the automatic stop function can be exerted, so that there is an effect equivalent to that of the third embodiment. .

In the fourth embodiment, as shown in FIG. 7B, the excitation result of the solenoid 13 is fed back to the output abnormality detecting means 33 and the output abnormality detecting means 35, respectively. You can The configuration of the automatic stop means 30 of the overload prevention device is applied to an electromagnetic proportional valve having a solenoid that is excited by an exciting current, as in the case of the first embodiment shown in FIG. 2B. It is a thing.

Embodiment 5 corresponding to claim 4 of the present invention
The configuration of the automatic stop means 30 of the overload prevention device according to the third embodiment will be described with reference to the block diagram of FIG.
The same components and those having the same function are denoted by the same reference numerals, and the configuration different from the third embodiment will be described. FIG. 5A according to the third embodiment and the fifth embodiment will be described. As is well understood in comparison with FIG. 8, the automatic stop means 3 having the configuration according to the third embodiment is provided.
The controller 23 that outputs a stop command to 0 can switch the output of the controller 23 to both the ON state and the OFF state to detect an abnormality in the main output means 32 or the sub output means 34 before performing the crane work. In order to recognize the timing, a power supply rise determination means 36 for detecting the power supply voltage of the overload prevention device 20 is provided.

Therefore, according to the automatic stop means 30 of the overload prevention device according to the fifth embodiment, the power supply rise determination means 36 for determining the rise of the overload prevention device brings the crane into the operable state. However, the main output means 3 can be known before the crane is activated, that is, before the crane is activated, that is, when automatic stop is not required.
It is possible to know the abnormality of the main output means 32 or the sub output means 34 by the outputs from the 2 and the sub output means 34, and the normal main output means 32 or the sub output means 34 can be utilized before the operation of the crane. This has the effect of preventing falls and damage in advance. The technical idea according to the fifth embodiment is not limited to that according to the fifth embodiment,
The present invention can be applied to any of the automatic stop means 30 having the configuration according to the first, second or fourth embodiment.

Embodiment 6 corresponding to claim 5 of the present invention
The configuration of the automatic stop means 30 of the overload prevention device according to the third embodiment will be described with reference to the block diagram of FIG.
The same components and those having the same functions are designated by the same reference numerals, and the configuration different from the third embodiment will be described. FIG. 5A according to the third embodiment and the sixth embodiment will be described. As well understood in comparison with FIG. 9, the automatic stopping means 3 having the configuration according to the third embodiment is provided.
The controller 23 that outputs a stop command to 0 can switch the output of the controller 23 to both the ON state and the OFF state to detect an abnormality in the main output means 32 or the sub output means 34 before the crane operation is performed. In order to recognize the timing, the crane operation state detecting means 37 for detecting the presence or absence of the crane operation by the operator is provided.

Therefore, according to the automatic stop means 30 of the overload prevention device according to the sixth embodiment, the crane operation state detection means 37 indicates that the crane is in an operable state but before the crane operation. When there is no need for automatic stop, the output from the main output means 32 and the sub output means 34 tells the abnormality of the main output means 32 or the sub output means 34. Since the main output means 32 or the sub output means 34 can be utilized, there is an effect that the crane can be prevented from tipping over or being damaged in advance, as in the case of the fifth embodiment. Of course, the technical idea according to the sixth embodiment can be applied not only to the sixth embodiment but also to any of the automatic stop means 30 having the configuration according to the first, second, or fourth embodiment. it can.

In the above description, the crane is a crawler type and the crane overload preventing device having a lattice type boom has been described as an example. However, a lower traveling body of a tire traveling type and a multi-stage telescopic boom are provided. Since the present invention can be applied to an overload prevention device for a wheel crane that the user has, the model to which the present invention is applied is not limited to the above embodiment.

[0044]

As described in detail above, the first aspect of the present invention
According to the crane overload prevention device of the present invention, even if the main output means becomes abnormal and the automatic stop actuating section cannot be operated, the output switching means switches from the main output means side to the sub output means side. According to the crane overload prevention device of the present invention, the overload prevention device functions normally because the sub-automatic stop operation part is activated by the sub-operation output output from the sub-output means. The output switching means switches from the main output means side to the sub output means side, and the auxiliary operation output output from the sub output means is operated through the second output switching means to operate the automatic stop operating portion. The load protection device works properly.

Therefore, claim 1 and claim 2 of the present invention
According to the crane overload prevention device of the related art, when an operation failure occurs in the operation stopping means and the operation of the boom or the like is not stopped, an alarm informs the operator that the operation stopping means is abnormal. Unlike the overload prevention device (operation control device) according to (1), the abnormal state is automatically restored to the normal state by the action of the output switching means, and the risk of tipping or failure of the crane due to overload is reliably avoided. Therefore, it can greatly contribute to the improvement of safety in crane work, and the output switching means and the output abnormality detecting means have a dedicated hardware configuration different from that of the computing means, resulting in excellent responsiveness. Since the reliability can be obtained, there is an excellent effect that the danger can be avoided quickly and surely. Of course, appropriate responsiveness and reliability can be obtained without using a hardware configuration.

According to the crane overload preventing apparatus of the third aspect of the present invention, in addition to the operation of the crane overload preventing apparatus according to the first or second aspect, the auxiliary output abnormality detecting means provides the auxiliary output means. The abnormality can be detected, and when a plurality of sub output means are provided, there is an effect that the automatic stop function can be exhibited by sequentially switching to another normal sub output means.

According to the crane overload prevention apparatus of the fourth or fifth aspect of the present invention, the crane is in the operable state by the power supply rise determination means for determining the rise of the computing means and the crane operation state detection means. However, it is possible to know that the crane is in operation. In other words, when there is no need for automatic stop, it is possible to know the abnormality of the main output means or the sub output means and to utilize the normal output means before the crane work, so prevent the crane from tipping or breaking in advance. It can be expected to have an excellent effect of being able to.

[Brief description of drawings]

FIG. 1 is a side view of a crane equipped with an overload prevention device according to Embodiment 1 of the present invention, and FIG. 1 (b) is a schematic configuration explanatory view of the overload prevention device.

2 relates to the first embodiment of the present invention, FIG.
(B) is a block diagram of an automatic stop means of the overload prevention device.

FIG. 3 relates to the first embodiment of the present invention, and FIG.
(B) is an explanatory view of the configuration of the output switching means.

4 relates to the first embodiment of the present invention, FIG.
(B) is an explanatory view of the configuration of the main output means (operation output output means).

FIG. 5 relates to a second embodiment of the present invention, and FIG.
(B) is a block diagram of the automatic stop means of an overload prevention apparatus.

FIG. 6 relates to a third embodiment of the present invention, FIG.
(B) is a block diagram of the automatic stop means of an overload prevention apparatus.

FIG. 7 relates to a fourth embodiment of the present invention, and FIG.
(B) is a block diagram of the automatic stop means of an overload prevention apparatus.

FIG. 8 is a block diagram of automatic stop means of an overload prevention device according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram of automatic stop means of an overload prevention device according to a sixth embodiment of the present invention.

[Explanation of Codes] 1 ... Lower traveling body, 2 ... Upper swing body, 3 ... Boom, 3a ...
Guide sheave, 3b ... Top sheave, 4 ... Gantry, 5
... Guy cable, 6 ... Upper spreader, 7 ... Lower spreader, 8 ... Boom hoisting drum, 9 ... Boom hoisting rope,
10 ... Winding rope, 11 ... Winding drum, 12 ... Hook, 13 ... Solenoid, 14 ... Sub solenoid 20, Overload prevention device, 21 ... Boom angle meter, 22 ... Load meter, 23 ... Controller 30, Auto stop means, 31 ... output switching means, 31a ... relay, 31b ... contact, 31c ... main contact, 31d ... auxiliary contact, 31 '... second output switching means, 31 "... output switching means, 32 ... main output means, 32a ... power supply for output Code, 3
2b ... Relay, 32c ... Output code, 32d ... Fuse, 32e ... Output transistor, 32f ... Overcurrent detection resistor, 32g ... Overcurrent protection circuit, 33 ... Output abnormality detection means, 34 ... Sub output means, 35 ... Sub Output abnormality detection means,
36 ... Power supply rise determination means, 37 ... Crane operation state detection means

Claims (5)

(57) [Claims] 1. The load of the suspended load obtained by the calculation is compared with the rated load, and it is determined that the load of the suspended load is heavier than the rated load and the crane may fall, and at the same time, the automatic stop operation part is stopped. In the crane overload prevention device, which comprises a calculation means for outputting a stop command, and an operation output output means for outputting an operation output for receiving the stop command and stopping the automatic stop operation part, the calculation means and the operation output An output switching means is provided between the output means and the auxiliary operation output output means for operating the auxiliary automatic stop actuating portion by receiving the stop command via the output switching means. And the operation output output from the operation output output means are compared, and if they do not match, it is determined that the operation output is abnormal, and the output switching means is switched from the operation output output means side to the sub-operation output output means side. An overload preventing device for a crane, which is provided with an output abnormality detecting means for operating the crane. 2. The load of the suspended load obtained by the calculation is compared with the rated load, and it is determined that the load of the suspended load is heavier than the rated load and the crane may fall down, and the automatic stop operation part is stopped. In the crane overload prevention device, which comprises a calculation means for outputting a stop command, and an operation output output means for outputting an operation output for receiving the stop command and stopping the automatic stop operation part, the calculation means and the operation output An output switching means is provided between the output means and the sub-operation output output means for receiving a stop command via the output switching means, and the stop command output from the computing means and the operation output output means are output. If the operation output is compared and if they do not match, it is judged that the operation output is abnormal, and output abnormality detection means for switching the output switching means from the operation output output means side to the auxiliary operation output output means side is operated. Second output switching means is provided for operating in cooperation with the output switching means and for receiving the normal operation output output from the operation output output means or the sub-operation output output means to operate the automatic stop operation part. An overload prevention device for cranes. 3. The stop command output from the computing means and the sub-operation output output from the sub-operation output output means are compared with each other, and when they do not match, it is determined that the sub-operation output is abnormal, and the output is output. The auxiliary output abnormality detecting means for switching the switching means from the side of the auxiliary operation output output means to the side of the other auxiliary operation output output means is provided, and the auxiliary output abnormality detecting means is provided. Crane overload protection device. 4. The output of the calculation means is in an ON state and an OFF state.
In order to recognize the timing at which the abnormality of the operation output output means or the auxiliary operation output output means can be detected before performing the crane work by switching to both the states, the power supply rise judgment means for judging the rise of the calculation means. The overload prevention device for a crane according to claim 1, wherein the overload prevention device is provided. 5. The output of the calculation means is in an ON state and an OFF state.
In order to recognize the timing at which an abnormality in the operation output output means or the sub-operation output output means can be detected before carrying out crane work, the operation means detects the operation state of the crane. The crane overload prevention device according to any one of claims 1, 2 and 3, further comprising a crane operation state detection means for determining a crane operation state.