JP2015187020A - Overload preventing device for mobile type crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overload preventing device for a mobile type crane that can prevent data on the overload preventing device in an external storage device from being lost.SOLUTION: An overload preventing device 2, configured to acquire a load to be applied to a crane and prevent the acquired load from surpassing a predetermined value corresponding to a posture of the crane, comprises a CPU 22 that reads out posture data from an external storage device 21, acquires a load corresponding to the posture of the crane and detects that the acquired load surpasses the predetermined value. The CPU 22 is provided with: a mirror copy portion 220 that copies separately a plurality of pieces of posture data stored in the external storage device 21 to the external storage device 21 so as to create a plurality of pieces of mirror posture data; a mirror data acquiring portion 221 that when an error occurs in the posture data acquired from the external storage device 21, acquires mirror posture data corresponding to the acquired posture data; and an overwriting portion 222 which overwrites the acquired mirror posture data as posture data of the external storage device 21.

Description

  The present invention relates to a safety device for a mobile crane, and more particularly, to an overload prevention device provided in a mobile crane for the purpose of preventing toppling and preventing damage to a boom and a jib.

  Self-propelled crawler cranes are known as mobile cranes. In a crawler crane (hereinafter simply referred to as a crane) having a long boom ranging from several meters to several tens of meters, the working radius varies depending on the boom length (boom length) and the inclination angle. In addition, in a crane equipped with a jib on the tip side of the boom, the working radius changes in accordance with the jib length (jib length) and the jib inclination angle in addition to the boom length and boom inclination angle. In accordance with the change in the working radius, the rated total load (allowable lifting load) that is the weight that can be lifted by the crane also changes.

If a load exceeding the rated total load is applied to the crane, the crane may fall over or the boom and jib may be damaged. Therefore, an overload prevention device (moment limiter) that prevents the load from exceeding the rated total load is applied to the mobile crane. ML) is equipped.
Patent document 1 is disclosing the overload prevention apparatus provided in a crane.
The overload prevention device disclosed in Patent Document 1 measures the actual load acting on the crane from the suspended load during the operation of the crane equipped with the boom, and changes the measured actual load and the tilt angle of the boom. In the crane overload prevention device designed to prevent the overload from acting on the crane based on the relationship with the total rated load of the crane that changes in accordance with the basis for determining the rated total load of the crane The operation mode setting permission switch with a key for shifting to the process of setting the operation mode setting item of the crane is provided.

  For example, as in the “work mode” disclosed in Patent Document 1, in order for the overload prevention device to obtain the rated total load of the crane, a so-called crane posture (configuration) such as a boom length or a jib length is used. It is necessary to know. For this purpose, the rated total load corresponding to changes in crane posture and boom and jib tilt angle is stored in the form of a table like the rated total load table. Have been accumulated. The overload prevention device reads the rated total load from the external storage device according to the crane posture, detects the load of the suspended load (suspended load), and compares the detected suspended load with the rated total load. Do.

Patent Document 2 discloses a nonvolatile storage device used as an external storage device that accumulates the rated total load table as described above.
The nonvolatile storage device disclosed in Patent Document 2 includes an error recognition / correction unit that recognizes the degree of deterioration of data stored in the nonvolatile memory, a control unit that controls the nonvolatile memory, and a swap prohibition area. A swap prohibition table to be managed, and a swap prohibition area dedicated refresh table, wherein the error recognition / correction unit has an error bit greater than or equal to a threshold value in data corresponding to a logical address stored in the swap prohibition area. When the controller determines that the error recognition / correction unit is greater than or equal to the threshold, the physical address stored in the refresh table dedicated to the swap prohibited area of the non-volatile memory is determined. Nonvolatile memory controller for swapping data corresponding to a logical address having an error bit greater than or equal to the threshold Characterized by comprising a storage unit having a rewritable non-volatile memory device.

JP 2011-105511 A JP 2011-203771 A

  In a crane provided with an overload prevention device (moment limiter) disclosed in Patent Document 1 or the like, there are various postures (configurations) that are combinations of booms and jibs. For this reason, data (referred to as ML data) showing the relationship between the crane variations and the changes in the boom and jib inclination angles and the changes in the rated total load are prepared in advance in the form of the above-mentioned rated total load table. I have to keep it. Therefore, the ML data is enormous in comparison with the size and computing capacity of the internal memory of the overload prevention device.

  This enormous amount of ML data is stored in advance in an external storage medium such as a nonvolatile storage device disclosed in Patent Document 2 (for example, smart media, an SD card, a compact flash (registered trademark), or the like). The overload prevention device acquires the rated total load corresponding to the crane posture from the ML data of the external storage medium, stores it in the internal memory, detects the load of the suspended load, and compares it with the rated total load.

  As described above, since the total amount of ML data stored in advance in the external storage device is enormous, the internal memory of the overload prevention device having a smaller capacity than this total amount must acquire and store all ML data. I can't. Therefore, the overload prevention device uses only the rated total load related to the current crane posture necessary for comparison with the suspended load from the ML data in an internal memory.

  On the other hand, whenever the boom and jib tilt angles change, the external storage device is accessed to read the current crane posture and the rated total load corresponding to the boom and jib tilt angles, and It is also possible to make a comparison. However, the time required for the CPU of the overload prevention device to access the external storage device is significantly longer than the time required to access the internal memory, so when accessing the external storage device, the overload prevention device is And the time required to compare the rated total load is very long. The comparison between the suspended load and the rated total load is performed to detect the overload applied to the crane. If this comparison takes time, the overload prevention device, which is the crane safety device, will be In some cases, the crane cannot be secured and the safety of the crane cannot be ensured.

Therefore, the overload prevention device copies and uses only the rated total load related to the current crane posture necessary for comparison with the suspended load, in order to perform computation as quickly as possible.
However, cranes are often used in the same posture for a long period of time, such as several months to several years, once the posture is determined. Therefore, if the overload prevention device accesses the external storage device and obtains the rated total load once, the rated total load is held inside, so the next months to several years to configure another posture There is no access to external storage.

  For this reason, even though the external storage device stores the rated total load corresponding to the crane variations of a huge number of variations, only a small part of the rated total load can be used. The current situation is that only the rated total load for only one posture is used. For this reason, the access from the overload prevention device to the external storage device is very high, such as once every several months to several years for a very small part of the total rated load included in the ML data. Only infrequent reading.

As is well known, an external storage device such as a nonvolatile storage device disclosed in Patent Document 2 has a configuration in which ML data is electrically stored and stored, so that the rated total load that is not accessed at all, It is not suitable for maintaining a rated total load that is accessed only for reading over a long period of time.
As a result, the ML data in the external storage device disappears with time, and the overload prevention device cannot acquire the rated total load corresponding to the changed crane attitude from the external storage device. If the rated total load cannot be acquired, the crane cannot be operated because the overload prevention device does not operate, so it is impossible to operate the crane by suppressing the disappearance of the rated total load in the external storage device. We must avoid this situation.

  In view of the above problems, an object of the present invention is to provide an overload prevention device for a mobile crane that can suppress loss of ML data in an external storage device.

In order to achieve the above-described object, the present invention takes the following technical means.
An overload prevention device for a mobile crane according to the present invention is an overload prevention device that acquires a load applied to the mobile crane and prevents the acquired load from exceeding a predetermined value according to the posture of the mobile crane. A first nonvolatile storage unit that is an external storage device that stores a plurality of posture data including the predetermined value used for comparison with the load for each posture of the mobile crane; and the first nonvolatile storage unit The attitude data is read out from the mobile crane, a load corresponding to the attitude of the mobile crane is acquired, and a control unit that detects that the acquired load exceeds the predetermined value is stored in the first nonvolatile storage unit. A temporary storage unit that temporarily stores posture data read by the control unit, and a plurality of storage units stored in the first nonvolatile storage unit. A second non-volatile storage unit that stores the attitude data stored in the temporary storage unit, and the control unit stores the first non-volatile storage unit in the first non-volatile storage unit. An error has occurred in the mirror copy unit that separately copies the plurality of posture data to the first nonvolatile storage unit to create a plurality of mirror posture data, and the posture data acquired from the first nonvolatile storage unit A mirror data acquisition unit that acquires mirror attitude data corresponding to the acquired attitude data, and an overwriting unit that overwrites the acquired mirror attitude data as attitude data of the first nonvolatile storage unit It is characterized by that.

  Here, the control unit other than the posture data read out for comparison with a load corresponding to the posture of the mobile crane among the plurality of posture data stored in the first nonvolatile storage unit. A partial reading unit that reads posture data in a predetermined order; and if the overwriting unit has no error in the posture data read by the partial reading unit, the posture data is stored in the first nonvolatile memory. If there is an error in the read attitude data, mirror attitude data corresponding to the attitude data is acquired from the first nonvolatile storage unit, and the acquired mirror The posture data may be overwritten as the posture data of the first nonvolatile storage unit.

  In addition, if there is no error in the posture data read by the partial reading unit, the overwriting unit overwrites the posture data as the posture data of the first nonvolatile storage unit, and the first data If there is an error in the read attitude data, the mirror attitude data corresponding to the attitude data is acquired from the first non-volatile memory and the acquisition is performed. The mirror attitude data thus overwritten may be overwritten as the attitude data of the first non-volatile storage unit and overwritten as the mirror attitude data of the first non-volatile storage unit.

Further, the partial readout unit obtains the identification information of the posture data most recently read out in the predetermined order among the plurality of posture data stored in the first nonvolatile storage unit. 2 It is good to memorize | store in the non-volatile memory | storage part and identify the attitude | position data read out next based on the identification information memorize | stored in the said 2nd non-volatile memory | storage part.
In addition, the overwriting unit may perform the overwriting at the time of startup or when referring to the attitude data of the first nonvolatile storage unit.

  According to the mobile crane overload prevention device of the present invention, the loss of ML data in the external storage device can be suppressed.

It is a figure showing roughly the whole crawler crane composition by the embodiment of the present invention. It is a block diagram which shows the structure of the overload prevention apparatus by this embodiment. It is a figure which shows ML data corresponding to the case where only a boom is provided in the upper turning body of the crawler crane by this embodiment. It is a figure which shows ML data corresponding to the case where the jib is provided in the front-end | tip of the boom of the crawler crane by this embodiment. It is a figure which shows the relationship between operation | movement and a structure of the overload prevention apparatus by this embodiment. It is a flowchart which shows operation | movement of the overload prevention apparatus by this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Although this embodiment demonstrates the overload prevention apparatus 2 of a mobile crane, before that, the crawler crane 1 which is a mobile crane with which the overload prevention apparatus 2 is provided is demonstrated.
With reference to FIG. 1, the structure of the crawler crane 1 by this embodiment is demonstrated. FIG. 1 is a diagram schematically showing the overall configuration of the crawler crane 1.

As shown in FIG. 1, a crawler crane 1 (hereinafter simply referred to as a crane 1) includes an upper swing body 10 and a lower travel body 11 that supports the upper swing body 10 from below so that the upper swing body 10 can swing and travel. .
The upper swing body 10 includes a swing frame 12 and a work device mounted on the swing frame 12. The working device is for performing a lifting operation (crane operation) for lifting a load (suspended load). Specifically, the working device includes a boom 13, a suspension rope 14, a hook device 15, a suspension winch (not shown), a mast 16, a hoisting rope 17, and a hoisting winch (not shown).

The boom 13 is attached to the front portion of the revolving frame 12 so as to be raised and lowered, and a hook device 15 for hanging a suspended load is suspended from the tip of the boom 13 via a suspension rope 14. The suspension winch is mounted on the revolving frame 12 and winds / unwinds the hook device 15 by winding / unwinding the suspension rope 14.
The mast 16 is provided on the rear part of the revolving frame 12. The hoisting winch is mounted on the revolving frame 12, and the boom 13 is raised and lowered by winding and unwinding the hoisting rope 17.

  A jib (not shown) for extending the boom length can be provided at the tip of the boom 13. The boom 13 is raised and lowered with respect to the upper turning body 10 by changing the angle with respect to the upper turning body 10, but the jib is raised and lowered with respect to the boom 13 by changing the angle with respect to the boom 13. If the jib is not provided, the working radius of the crane 1 which is the turning radius of the hook device 15 around the upper swing body 10 is determined by determining the angle of the boom 13. If the jib is provided, the working radius of the crane 1 is determined by determining the angle of the boom 13 and then the angle of the jib.

That is, the working radius of the crane 1 is a value determined by the inclination of the boom 13 and the jib. If the suspended load (that is, the load applied to the crane 1) is constant, the larger the working radius, the larger the working radius. The moment generated is large, and the crane 1 may fall over and the boom 13 and jib may be damaged.
Therefore, the rated total load that is the upper limit of the load of the suspended load that can be suspended by the crane 1 is determined by the working radius and the posture of the crane 1 (in combination with the length of the boom 13 and the jib).

Below, with reference to FIG. 2, the structure of the overload prevention apparatus 2 is demonstrated. FIG. 2 is a block diagram showing a configuration of the overload prevention device 2 constituted by a microcomputer or the like.
The overload prevention device 2 acquires a load such as a suspended load applied to the crane 1 according to the posture of the crane 1 and prevents the acquired load from exceeding a predetermined value, and is the predetermined value. A computing device 20 that prevents the crane 1 from lifting a suspended load that exceeds the rated total load based on the rated total load, and an external storage device (first nonvolatile storage unit) 21 that stores and stores the rated total load. ing.

Before describing the configuration of the arithmetic device 20, the configuration of the external storage device 21 that stores the rated total load will be described with reference to FIG.
The external storage device 21 is a device that stores a plurality of posture data including the above-described rated total load, which is a predetermined value used for comparison with a load applied to the crane 1, for each posture of the crane 1. The posture data will be described later.

  The external storage device 21 is a non-volatile semiconductor memory composed of a flash memory composed of a plurality of physical blocks, and is arranged outside the arithmetic device 20. The physical block is a data erasing unit and is composed of a plurality of memory cells. As the external storage device 21, for example, a nonvolatile storage device disclosed in the above-described Japanese Patent Application Laid-Open No. 2011-203771 can be used. The external storage device 21 reads and writes data in accordance with a read instruction and a write instruction from the arithmetic unit 20 that is a host device.

The external storage device 21 stores ML data (moment limiter data) that can be expressed in the form of tables as shown in FIGS. The ML data is a set of rated total loads corresponding to the working radius of the crane 1 determined by the inclination (tilt angle) of the boom 13 and jib in the posture for each posture of the crane 1 that is a combination of the boom 13 and the jib.
Here, FIG. 3 shows ML data corresponding to the case where only the boom 13 is provided on the upper swing body 10 as the posture of the crane 1, and FIG. 4 shows the jib at the tip of the boom 13 as the posture of the crane 1. ML data corresponding to the case where is provided.

  The ML data shown in FIG. 3 is composed of a plurality of rated total loads corresponding to a working radius of 6.0 to 70.0 m for every 10 boom lengths of 30.0 to 84.0 m as the posture of the crane 1. Has been. The ML data shown in FIG. 4 includes a plurality of pieces corresponding to a working radius of 16.0 to 78.0 m for each of five types of jib lengths of 24.0 to 66.0 m provided on the boom 13 having a length of 30.0 m. It consists of the rated total load. The ML data in FIG. 4 is composed of a plurality of rated total loads for each inclination (inclination angle) of the three types of booms 13 of 66 to 86 degrees in one jib length.

  That is, if the attitude of the crane 1 is determined by the length of the boom 13 provided in the crane 1, the presence or absence of the jib, and the length of the jib, the ML data on the attitude is referred to in the ML data of FIGS. From the acquired ML data, the rated total load corresponding to the working radius of the crane 1 determined by the inclination (tilt angle) of the boom 13 and the jib can be acquired.

  As shown in FIG. 2, the external storage device 21 classifies and stores the ML data shown in FIGS. 3 and 4 described above so that it can be read for each posture of the crane 1. The external storage device 21 has a plurality of rated total loads corresponding to a boom length of 30.0 m, which is one boom length, as shown by a thick line L1 in FIG. A plurality of rated total loads corresponding to a jib length of 24.0 m, which is one jib length in a boom 13 of 0 m, are stored as, for example, one data file (posture data file) corresponding to the posture of the crane 1. Can do.

  FIG. 2 shows a state in which the external storage device stores a plurality of posture data files in a part of the storage area. Each of the regions 210 surrounded by a rectangle is assigned to one posture of the crane 1. A state is shown in which one posture data file storing a plurality of corresponding rated total loads is stored in association with each other. The arithmetic unit 20 to be described later can read out, for example, a region 210 in which a posture data file corresponding to the posture of the crane 1 is surrounded by a rectangle. Here, the posture data file itself may be referred to as posture data as data corresponding to the posture of the crane 1.

As shown in FIG. 2, the computing device 20 is a device that prevents the crane 1 from lifting a suspended load exceeding the rated total load based on the rated total load, and is a central processing unit CPU (control unit). 22, a RAM 23 that is a temporary storage unit configured by a volatile memory, and a ROM 24 that is a second nonvolatile storage unit configured by a nonvolatile memory.
The CPU 22 reads posture data from the external storage device 21, acquires a load corresponding to the posture of the crane 1, and detects that the acquired load exceeds a predetermined value. Specifically, the CPU 22 reads out the posture data (that is, the rated total load) corresponding to the posture of the crane 1 from the external storage device 21, and the read rated total load and the suspended load detected by the overload prevention device 2. Compare the load (load). By this comparison, when the load of the suspended load is likely to exceed the rated total load at the working radius of the crane 1, the CPU 22 issues a warning before exceeding the rated total load, and the load of the suspended load is the rated total load. Is exceeded, a command for stopping the operation of the crane 1 (slow stop) is output to the drive system of the crane 1. The CPU 22 can avoid breakage or overturn of the crane 1 by preventing an excessive load from acting on the crane 1 by the above-described operation.

The boom 13 or the jib length actually used for the crane work is, for example, via the operation panel (not shown) of the overload prevention device 2 provided in the cab of the crane 1 or the like. Then, it is input to the overload prevention device 2 by an operator of the crane 1 or the like.
The CPU 22 that performs such an operation includes a mirror copy unit 220, a mirror attitude data acquisition unit 221, and an overwrite unit 222, which will be described in detail below, and prevents the loss of attitude data in the external storage device 21.

The mirror copy unit 220 separately creates a plurality of mirror posture data by separately copying a plurality of posture data stored in the external storage device 21 that is the first nonvolatile storage unit to the external storage device 21. That is, the mirror copy unit 220 creates mirror attitude data that is a copy of the attitude data.
The mirror attitude data acquisition unit 221 has an error in the attitude data corresponding to the current attitude of the crane 1 read (acquired) from the external storage device 21 by the CPU 22 in order to compare the rated total load and the suspended load. When this occurs, mirror attitude data having the same contents corresponding to the acquired attitude data is acquired.

  The overwriting unit 222 overwrites at least the mirror attitude data acquired by the mirror attitude data acquisition unit 221 as attitude data of the external storage device 21 and further overwrites it as mirror attitude data of the external storage device 21. The overwriting unit 222 refreshes the posture data and the mirror posture data that are electrically held in the external storage device 21 and are accessed less frequently by this overwriting, and the posture data and the mirror posture data (that is, ML data) are lost. To prevent. Here, “overwrite” refers to a write operation that replaces (updates) existing data with another new data.

  The RAM 22 and the ROM 24 are connected to the CPU 22 having such a configuration. The RAM 23 is a volatile temporary storage memory (temporary storage unit) having a capacity smaller than the entire capacity of the plurality of posture data stored in the external storage device 21, and the posture data read out from the external storage device 21 by the CPU 22. Temporarily store and hold. The ROM 24 is a non-volatile memory (second non-volatile storage unit) having a capacity smaller than the entire capacity of the plurality of posture data stored in the external storage device 21, and the CPU 22 instructs the posture data held by the RAM 23, for example. The data to be stored is stored and retained even after the power to the arithmetic unit 20 is cut off.

In the arithmetic device 20 having the above-described configuration, the CPU 22 further includes a partial reading unit 223.
The partial reading unit 223 has predetermined posture data other than the posture data read out for comparison with the load corresponding to the posture of the crane 1 among the plurality of posture data stored in the external storage device 21. Read in order. Specifically, the partial reading unit 223 includes a plurality of pieces of data stored in the external storage device 21 separately from the reading of the posture data corresponding to the current crane posture for comparing the rated total load and the suspended load (load). A part of the posture data is read out in a predetermined order. The order of the posture data read by the partial reading unit 223 can be arbitrarily determined, and may be an order based on the posture of the crane 1 such as the length of the boom 13 and the jib, or data attributes such as the size of the posture data and the number of the physical block. The order may be based on information about the.

  Here, the overwriting unit 222 is also linked with the partial reading unit 223. The overwriting unit 222 determines whether or not an error has occurred in the posture data read by the partial reading unit 223. If no error has occurred in the posture data, the posture data is used as the posture data of the external storage device 21. Overwrite. On the other hand, if an error has occurred in the read posture data, the overwriting unit 222 acquires mirror posture data corresponding to the posture data from the external storage device 21, and stores the acquired mirror posture data in the external storage. It is overwritten as the attitude data of the device 21.

  Further, if there is no error in the posture data read by the partial reading unit 223, the overwriting unit 222 overwrites the posture data as the posture data of the external storage device 21 and also as the mirror posture data of the external storage device 21. Overwrite. On the other hand, if an error has occurred in the read posture data, the overwriting unit 222 acquires mirror posture data corresponding to the posture data from the external storage device 21, and stores the acquired mirror posture data in the external storage. It is overwritten as the attitude data of the device 21 and is overwritten as the mirror attitude data of the external storage device 21.

With reference to FIGS. 5 and 6, the operation of the overload prevention device 2 including the arithmetic device 20 and the external storage device 21 having the above-described configuration will be described. FIG. 5 is a diagram showing the relationship between the operation and the configuration of the overload prevention device 2, and FIG. 6 is a flowchart showing the operation of the overload prevention device 2.
First, when the power is turned on and the overload prevention device 2 is activated, the CPU 22 of the arithmetic unit 20 stores in the ROM 24 posture data corresponding to the posture of the crane 1 currently set in the overload prevention device 2. Confirm whether or not. If the posture data corresponding to the current posture of the crane 1 is stored in the ROM 24, the stored posture data is expanded in the RAM 23. On the contrary, if the posture data corresponding to the current posture of the crane 1 is not stored, the CPU 22 notifies the operator that there is no posture data in the ROM 24 and stops all crane operations. The operator sees the state and tries to reset itself, and the CPU 22 of the arithmetic unit 20 receiving the setting instruction accesses the external storage device 21 as shown by the broken line a in FIG. Posture data corresponding to the posture of the crane 1 is read out and developed in the RAM 23 (step S10).

By the processing in step S10, the overload prevention device 2 can prevent the crane 1 from lifting a suspended load exceeding the rated total load based on the rated total load.
The mirror copy unit 220 of the CPU 22 checks whether or not the external storage device 21 has already saved the mirror attitude data (step S20).
If the external storage device 21 does not store the mirror posture data (in the case of “no” in step S20), the mirror copy unit 220 stores all of the plurality of posture data stored in the external storage device 21 as the external storage device. By separately copying the data into the 21, as shown in FIG. 5, a plurality of mirror attitude data are created and stored as replicas corresponding to the plurality of attitude data. (Step S30).

  If it is determined in the process of step S20 that the external storage device 21 has already stored the mirror attitude data (in the case of “yes” in step S20), the partial reading unit 223 will store the attitude stored in the external storage device 21. Data is read in a predetermined order. At this time, the partial reading unit 223 confirms whether the identification information (physical block number or the like) of the posture data read most recently along a predetermined order is stored in the ROM 24. The partial reading unit 223 reads the physical block number if the physical block number is stored in the ROM 24, and if the physical block number is not stored, the partial reading unit 223 reads the physical block number to be read first in a predetermined order ( For example, the smallest physical block number) is read (step S40).

  The partial reading unit 223 performs the posture data next to the posture data corresponding to the physical block number read from the ROM 24 in step S40 in a predetermined order (hereinafter referred to as “next posture data”) in FIG. The overwriting unit 222 determines whether or not an error has occurred in the read “next posture data” (step S50).

In the process of step S50, the partial reading unit 223 identifies "next attitude data" that is attitude data to be read next based on the physical block number that is identification information of attitude data stored in the ROM 24. It can be said.
If no error has occurred in step S50, the overwriting unit 222 develops the “next posture data” read by the partial reading unit 223 on the RAM 23 (step S60).

Following step S60, the overwriting unit 222 overwrites the “next posture data” in the external storage device 21 with the “next posture data” expanded on the RAM 23, as indicated by the solid line d in FIG. 5, the mirror attitude data corresponding to the “next attitude data” is overwritten (step S70).
Here, if an error has occurred in the above-described step S50, the overwriting unit 222 follows the reverse direction of the solid line c in FIG. 5 and the mirror corresponding to the “next posture data” read by the partial reading unit 223. The attitude data is read and developed on the RAM 23 (step S80).

Subsequent to step S80, the overwriting unit 222 stores the mirror attitude data corresponding to the “next attitude data” developed on the RAM 23 in the external storage device 21 as “next attitude data” as indicated by the solid line d in FIG. The data is overwritten, and the mirror attitude data corresponding to the “next attitude data” is also overwritten as indicated by the solid line c in FIG. 5 (step S90).
When overwriting in step S70 or step S90 is completed, the overwriting unit 222 stores the physical block number, which is identification information of the overwritten “next posture data”, in the ROM 24, and stores the physical block number already stored. Update (step S100).

The overwriting unit 222 of the CPU 22 traces the posture data corresponding to the current posture of the crane 1 read in step S10 in the reverse direction of the broken line a in FIG. 5 when the overload prevention device 2 is turned off. Thus, the attitude data of the external storage device 21 is overwritten, and the mirror attitude data corresponding to the attitude data is also overwritten as indicated by the solid line e in FIG.
Further, the CPU 22 stores the posture data corresponding to the current posture of the crane 1 developed in the RAM 23 in the ROM 24 when the overload preventing device 2 is turned off. As a result, the next time the overload prevention device 2 is powered on, the CPU 22 can read the attitude data stored in the ROM 24 and develop it in the RAM 23 without accessing the external storage device 21.

The overload prevention apparatus 2 according to the present embodiment can create mirror attitude data that is a backup of attitude data by performing the above-described steps S20 and S30 by the mirror copy unit 220.
In addition, by performing the above-described steps S50 to S100 by the partial reading unit 223 and the overwriting unit 222, an enormous amount of posture data is sequentially changed according to a predetermined order based on, for example, a physical block number. Access and rewrite can be performed. Specifically, even if an error occurs in the posture data, it can be repaired by overwriting the posture data in which the error has occurred with the mirror posture data as a backup.

  Furthermore, the partial reading unit 223 and the overwriting unit 222 overwrite the posture data and the mirror posture data with the posture data in which no error has occurred, even if no error has occurred in the posture data. To refresh. By this refresh, it is possible to prevent posture data that is not accessed at all for a very long time, and to suppress the loss of the rated total load (that is, ML data) that is posture data in the external storage device 21.

  However, when the processing of steps S20 to S100 is performed while the crane 1 is operating, the overload prevention device 2 that should be performed originally is to compare the suspended load and the rated total load to prevent the crane 1 from being overturned and damaged. Therefore, the safety of the crane 1 may not be ensured. Therefore, the arithmetic unit 20 performs steps S20 to S100 only during the preparation period for the operation of the overload prevention device 2, such as when the overload prevention device 2 is activated or terminated, or when the posture data is referred to the external storage device 21. Processing may be performed in parallel. In particular, the overwriting unit 222 may overwrite the posture data or the mirror posture data when the overload prevention device 2 is activated or when the posture data is referred to the external storage device 21.

  Each embodiment disclosed this time should be considered as illustrative in all points and not restrictive. In particular, in each embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of the constituents are within the range normally practiced by those skilled in the art. It does not deviate and employs a value that can be easily assumed by those skilled in the art.

  For example, in the above-described embodiment, the overwriting unit 222 determines whether or not an error has occurred in the posture data read by the partial reading unit 223. The determination of this error is performed by partial reading by reading the posture data. Part 223 may do this.

DESCRIPTION OF SYMBOLS 1 Crawler crane 2 Overload prevention apparatus 10 Upper revolving structure 11 Lower traveling structure 12 Revolving frame 13 Boom 14 Hanging rope 15 Hook apparatus 16 Mast 17 Hoisting rope 20 Arithmetic apparatus 21 External storage apparatus 22 CPU (control part)
23 RAM
24 ROM
210 Region 220 Mirror Copy Unit 221 Mirror Attitude Data Acquisition Unit 222 Overwrite Unit 223 Partial Reading Unit

Claims (5)

An overload prevention device that acquires a load applied to the mobile crane and prevents the acquired load from exceeding a predetermined value according to the posture of the mobile crane,
A first nonvolatile storage unit that is an external storage device that stores a plurality of posture data including the predetermined value used for comparing with the load for each posture of the mobile crane;
A controller that reads out the attitude data from the first non-volatile storage unit, acquires a load according to the attitude of the mobile crane, and detects that the acquired load exceeds the predetermined value;
A temporary storage unit that temporarily stores posture data read out by the control unit, having a capacity smaller than the entire capacity of the plurality of posture data stored in the first nonvolatile storage unit;
A second nonvolatile storage unit that has a capacity smaller than the entire capacity of the plurality of posture data stored in the first nonvolatile storage unit and stores the posture data stored in the temporary storage unit;
The control unit is
A mirror copy unit that separately copies a plurality of posture data stored in the first nonvolatile storage unit to the first nonvolatile storage unit to create a plurality of mirror posture data;
A mirror data acquisition unit that acquires mirror attitude data corresponding to the acquired attitude data when an error has occurred in the attitude data acquired from the first nonvolatile storage unit;
An overload prevention device for a mobile crane, comprising: an overwriting unit that overwrites the acquired mirror attitude data as attitude data of the first nonvolatile storage unit. Of the plurality of posture data stored in the first non-volatile storage unit, the control unit stores posture data other than the posture data read for comparison with a load corresponding to the posture of the mobile crane. A partial reading unit for reading in a predetermined order;
If there is no error in the posture data read by the partial reading unit, the overwriting unit overwrites the posture data as the posture data of the first nonvolatile storage unit, and the read posture If an error occurs in the data, the mirror attitude data corresponding to the attitude data is acquired from the first nonvolatile storage unit, and the acquired mirror attitude data is overwritten as the attitude data of the first nonvolatile storage unit The overload prevention device for a mobile crane according to claim 1.   If there is no error in the posture data read by the partial reading unit, the overwriting unit overwrites the posture data as the posture data of the first nonvolatile storage unit, and the first nonvolatile memory If there is an error in the read attitude data, the mirror attitude data corresponding to the attitude data is acquired from the first nonvolatile storage unit and the acquired mirror is overwritten as the mirror attitude data of the storage unit The overload of the mobile crane according to claim 2, wherein the attitude data is overwritten as the attitude data of the first nonvolatile storage unit and is overwritten as the mirror attitude data of the first nonvolatile storage unit. Prevention device.   The partial readout unit obtains the identification information of the posture data read most recently in the predetermined order among the plurality of posture data stored in the first nonvolatile storage unit. 4. The mobile crane according to claim 3, wherein the attitude data to be read next is identified based on the identification information stored in the second nonvolatile storage and stored in the second nonvolatile storage. Load prevention device. 5. The overload prevention of the mobile crane according to claim 2, wherein the overwriting unit performs the overwriting at the time of start-up or when referring to the posture data of the first nonvolatile storage unit. apparatus.

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