JP2002080189A - Overload preventing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overload preventing device which can prevent damage and deformation of a crane part by grounding a load levitated in the air by an overloaded condition to the former position by falling movement action of a boom, in this way, to avoid maintaining of a crane for a long time in the overloaded condition. SOLUTION: This overload preventing device 1 is provided with an arithmetic control part 6, after judging whether a ground cut flag is turned on or not, judging whether a detection result from an actual load detection part 2 exceeds a permissible load value or not, to set objective operation outputting a stop signal. The arithmetic control part 6 sets either of boom hoisting operation or boom falling operation as the operation in a, stop direction. After the stop direction is set, the present operating direction is determined to be based on a detection result from a boom hoisting operation detection part 5a or a boom falling operation detection part 5b, when the determined operating direction is equal to the set stop position, a stop signal is output to an automatic stop means 7. In the other hand, when the determined operating direction is different, operation in the present operating direction is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing an overload of a boom of a work vehicle, and more particularly, to an overload state after the operation of a boom raising / lowering operating lever is switched from a state of stopping the raising / lowering to a state of a raising operation. The present invention relates to an overload prevention device that allows a boom lowering operation up to a boom raising and lowering angle before switching.

[0002]

2. Description of the Related Art Usually, a crane which performs various work operations such as expansion and contraction or undulation of a boom suspending a load such as a container and hoisting of a load by a winch is provided with an overload prevention device.
Prevents the crane from overturning or breaking during overload. When the overload prevention device recognizes an overload state, various operations such as a boom lowering operation, a boom extension operation, and a winch hoisting operation are uniformly prohibited regardless of the crane state at the time of overload. This prevents the load from being further applied and prevents the crane from being damaged or deformed. However, there is a problem that it takes time to return the operation permitted for the subsequent work.

[0003] With respect to such a conventional overload prevention device, the present applicant has disclosed that when the load is unloaded from a high place, the load is temporarily lifted from that position, and when the overload is caused by an operation of raising a boom. In the case where the operation of the crane is stopped and the predetermined condition is satisfied by the downward operation of the boom, that is, when the increase in the boom radius or the load factor applied to the boom within a certain time is equal to or less than a certain value,
A proposal has been made to allow the boom down operation continuously, while prohibiting the boom down operation when it exceeds a certain value to avoid further increase in the load (Japanese Patent Application No. 11-63).
574). In such a proposal, attention is paid to the fact that there is a case where the load can be quickly grounded when the boom is turned down, and the load can escape from the overload state.

[0004] However, in the above proposal, if the predetermined condition is not satisfied in the overload state, the boom down operation is prohibited, and the load may not be able to touch the ground. It cannot be removed and the work efficiency is reduced. In addition, when an overload occurs, the work may be stopped automatically because the work is automatically stopped once. In particular, as shown in FIG. 4, the crane 40 using the searcher hook 41 raises and lowers the load 43 not by a winch operation but by an increase or a decrease in the boom raising and lowering angle θ due to a raising and lowering operation of a boom 44. When the boom down operation is prohibited, the subsequent work is interrupted, and it is expected that work efficiency will be reduced.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a load or space that is not completely suspended in the air when it is overloaded at the time of, for example, a high-altitude ground-break operation. The present invention provides an overload prevention device which can bring a load floating on a ground to a position before groundbreaking by a downward operation of a boom, so that a crane can be quickly released from an overload state.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned object, and its gist is to provide a boom load detecting means for detecting a load value applied to a boom of a working vehicle, and an elevation angle of the boom. Boom undulation angle detecting means for detecting
A boom operation detecting means for detecting whether the operation of the boom indicates a boom raising operation, a boom lowering operation, or a boom operation stop; and a boom based on each detection result from the load detecting means and the elevation angle detecting means. And a boom operation control unit for stopping the operation of the overload control unit, wherein the operation control unit detects a switch from the stop of the boom operation to the boom raising operation based on a detection result of the operation detection unit. Means, and storage means for storing a boom undulation angle when the switch detection means detects the switching, wherein when the detection result of the boom undulation angle detection means is equal to or greater than the stored boom undulation angle, the boom load is stored. If the detection result by the detecting means exceeds the allowable load value of the boom due to the boom raising operation, the boom raising operation is stopped, and Serial in overload preventing apparatus characterized by allowing prone operation of the boom up boom hoisting angle stored.

[0007]

The overload prevention device of the present invention can detect the load value applied to the boom of the work vehicle and the boom undulation angle, and switch the operation of the boom from the stop of the boom operation to the boom raising operation. If the boom up / down angle at the time of the boom increases and the load value exceeds the boom allowable load value, stop the boom up operation and stop the boom operation by allowing the boom down operation up to the boom up / down angle. I try to make it.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an overload prevention device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of an overload prevention device of the present invention provided in a crane truck. As shown in FIG. 1, the overload prevention device 1 includes an actual load detection unit 2 that detects a load value applied to a crane boom, and a boom elevation angle detection unit 3 that detects a boom elevation angle θ (FIG. 4). And a boom length detector 4 for detecting the length of the boom. The overload prevention device 1 also includes a detection unit 5 that detects whether the boom raising / lowering operation lever is instructing the boom raising operation, the boom stop operation, or the boom lowering operation. It is composed of a boom raising operation detecting unit 5a for detecting that the instruction of the lever is a boom raising operation, and a boom lowering operation detecting unit 5b for detecting that it is a boom lowering operation. For example, when a boom raising operation lever is instructed by the boom raising / lowering operation lever, the boom raising operation detecting unit 5a detects the instruction and instructs a boom lowering operation unit (not shown) to perform a boom lowering operation.

The overload prevention device 1 further includes an arithmetic control unit 6 for performing various calculations based on the detection results from the detection unit 2-5 and controlling the boom operation. For example, a CPU executes a routine program described later shown in FIGS. 2 and 3 and stores data used or generated at the time of execution and data from each of the detection units.

Further, the arithmetic control unit 6 detects that the switch from the boom hoisting stop to the hoisting operation has been made by turning on the grounding flag on the setting routine program shown in FIG. Elevation angle detector 3
It is further detected that the boom up / down angle (landing start angle) detected by the above has increased or decreased. If the detected result indicates an increase in the boom angle, the stop signal for stopping the boom raising operation when the detected result by the actual load detection unit 2 after the increase exceeds the boom allowable load value. Is output to the automatic stop means 7, and the automatic stop means 7 stops the boom raising operation. In addition to the boom raising operation, the automatic stop means 7 performs a boom lowering operation, a boom extension operation, and an automatic stop of winch winding based on a corresponding stop signal from the arithmetic control unit 6 based on a predetermined drive unit (not shown). To automatically stop the operation. In the present specification, “automatic stop” assumes that the corresponding operation is stopped regardless of the instruction of each operation lever. The arithmetic control unit 6 includes an automatic stop unit 7.
An instruction can be output to the alarm means 8 for issuing an alarm when each operation is stopped. Further, the detection result of the boom length detector 4 is used for calculating the actual load and selecting the limit load.

FIG. 2 is a schematic flowchart of a routine in which the arithmetic control unit 6 of FIG. 1 outputs a stop signal. As shown in this flow, after executing a later-described land separation flag setting routine (step S21), it is determined as a stop condition of the boom operation whether or not the detection result from the actual load detection unit 2 exceeds the allowable load value. (Step S22), and in the case of No,
It repeats from step S21 of this routine. In the case of Yes, it is determined whether or not the processing result in step S21 has turned on the ground separation flag (step S23). In the case of Yes, the operation of the arithmetic control unit 6 to output the stop signal, that is, the stop is performed. Boom operation as direction operation,
A boom extension operation and a winch winding operation are set (step S24). On the other hand, if No, the boom down operation, the boom extension operation, and the winch winding operation are set (step S25). After the stop direction is set, in the case of the boom raising / lowering operation, the current operation direction is boom-raised, and the current operation direction is determined based on the detection result from the operation detector 5a or the boom lowering operation detector 5b. It is determined whether the direction is the stop direction (step S2).
6). Then, in the case of Yes, the arithmetic control unit 6 outputs a stop signal to the automatic stop means 7 (step S27),
In this case, the processing of this routine is repeated. Here, in steps S24 and S25, the boom extension operation and the winch winding operation are set regardless of the on / off state of the ground separation flag, and it is determined in step S26 that these operations are the same as the current operation direction. Then, step S2
At 7, a stop signal for stopping the operation corresponding to the operation is output to the automatic stop means 7.

FIG. 3 is a schematic flow chart of a setting routine for setting the partitioning flag shown in FIG. As shown in this flow, first, it is determined whether or not the ground separation flag is in an on state (step S31). In the case of No, it is determined whether or not the boom raising / lowering operation lever has changed from the boom stop position to the raised position. The determination is made based on the detection results of the detection units 5a and 5b (step S32). In the case of Yes, the actual load value WA, which is the detection result from the actual load detection unit 2, is a small load value W1 that is composed of the load of the hanger or the like and the error of the detection result.
It is determined whether or not (WA ≦ W1) (step S33). In this step S33, it can be determined that the crane is in the ground-cut state, and if Yes, the ground-break flag is set to the ON state (step S34), and the detection from the boom hoisting angle detector 3 at this time is performed. After storing the resulting boom hoisting angle θ as the ground-cutting start angle θ1 (step S35), the process exits this setting routine and proceeds to step S22 in FIG. Determination steps S32 and S33
In the case of No, it is determined that the vehicle is not in the ground-cutting state and the boom-down operation is prohibited, and the process exits from the setting routine and proceeds to step S22 in FIG. In this setting routine, step S32 is provided, in which the minute load value W1 is considered. However, a detection result in which the minute load is considered in advance by the detection unit without using that step may be used.

On the other hand, in the case of Yes in step S31, it is determined whether or not the boom raising / lowering operation lever is at the raised position based on the detection result from the detector 5a (step S36). In the case of Yes in step S36, the boom hoisting angle θ, which is the detection result from the boom hoisting angle detection unit 2, is equal to the ground start angle θ1 stored in step S35, the extension of the crane rope, and the bending of the crane parts. The amount of change in the boom undulation angle Δθ (for example, 5
) Is determined (θ ≧ θ1 + Δθ) (step S37). In this step S37, Ye
In the case of s, the ground separation flag is reset to the off state (step S38), and this setting routine is exited to prohibit the boom down operation, and the process proceeds to step S22 in FIG.
On the other hand, in the case of No, this setting routine is exited to stop the boom raising operation, and the process proceeds to step S22 in FIG.
In this setting routine, the change Δθ is considered in step S37, but the detection unit may output a detection result in consideration of the error in advance, and use the result to determine in this step. Further, the change Δθ also depends on the detection result of the boom length detector 4.

On the other hand, in the case of No at step S36, it is determined whether or not the boom raising / lowering operating lever is at the protruding position (step S39). And step S3
In the case of Yes in 9, it is determined whether or not the boom up-and-down angle θ as the detection result from the boom up-and-down angle detection unit 3 is equal to or smaller than the ground-cutting start angle θ1 (step S40). The up / down operation lever is at the stop position, exits this setting routine, and proceeds to step S22 in FIG.

In step S40, it is possible to determine whether to continue the boom lowering operation or allow the boom lowering operation. In the case of No, the boom raising and lowering angle θ is larger than the ground starting angle θ1. The flag is maintained in the ON state, and the continuation of the boom down operation or the boom down operation is permitted. On the other hand, in the case of Yes, in order to stop the boom down operation, the ground separation flag is reset to an off state (step S38), and the process proceeds to step S22 in FIG.

As described above, the operation of the overload prevention device according to the present invention can be implemented by a program, and can be implemented by simple software processing as compared with the software processing used in the above proposal by the present applicant. It is. Also, unlike the conventional overload prevention device which determines the state of the groundbreak after the automatic stop of the work operation at the time of overload, the state of the groundbreak is determined before the automatic stop, so that a quick crane operation is possible, and Efficient work can be realized. In addition, the load after the ground cut, boom down operation other than boom raising operation,
If the overload occurs during the boom extension operation or the boom swing operation, or if the load is overloaded due to an error such as the load being shaken by the load or the like, the boom down operation, Since the boom extending operation and the winch hoisting operation are stopped to enable the boom raising operation, the boom retracting operation, and the winch lowering operation, an overload state of the crane can be avoided.

Here, in the routine program of the present embodiment, as shown in FIG. 4, the angle formed between the boom 44 that lifts the load 43 at a high place by the searcher hook 41 and the reference surface 45 of the crane 40 is the boom hoisting angle θ. However, the present invention can also be applied to the case where a load lower than the reference surface 45 is grounded, by treating the magnitude (absolute value) of the angle between the boom 44 and the reference surface 45 as the boom undulation angle. Further, in the present embodiment, it is assumed that the boom raising operation is an operation of raising the load, and the boom down operation is an operation of lowering the load.

[0018]

According to the overload prevention device according to the present invention,
For example, in the work of unloading a load from a high place by the boom operation, if the load becomes overloaded during the boom boom operation, before the unbundling, the load that does not completely float in the air or the load that floats in the air Can be grounded by the downward movement of the boom, so that the crane can be prevented from being maintained in an overloaded state for a long time, and the crane portion can be prevented from being damaged or deformed.

Further, since the boom undulation angle which can be achieved by the boom undulation operation in the direction of decreasing the load when the terrain starts is up to the terrain start angle, when the terrain start surface changes, for example, Even if the truck moves immediately after the ground is removed from the truck bed at a high altitude, the load does not drop below the height of the bed, which is the ground cut surface, and gives a moment to the boom that exceeds the boom moment applied at the start of the ground cutting. Since there is no boom, deformation and damage of the boom can be avoided. In addition, by returning the truck to the original position again, the load can be easily placed on the carrier.

[Brief description of the drawings]

FIG. 1 is a block diagram of an overload prevention device of the present invention provided in a crane truck.

FIG. 2 is a schematic flowchart of a routine in which a calculation control unit 6 of FIG. 1 outputs a stop signal.

FIG. 3 is a schematic flowchart of a setting routine for setting a ground separation flag in FIG. 2;

FIG. 4 is a schematic view of a crane using a searcher hook.

Claims (1)

[Claims] 1. A boom load detecting means for detecting a load value applied to a boom of a work vehicle, a boom hoisting angle detecting means for detecting an hoisting angle of the boom, and the operation of the boom is a boom raising operation and a boom lowering operation. Boom operation detection means for detecting which one of the following is instructed to stop the boom operation: boom operation control means for stopping the operation of the boom based on each detection result from the load detection means and the elevation angle detection means. In the overload prevention device, the operation control unit detects a switch from a stop of the boom operation to a boom raising operation based on a detection result of the operation detection unit, and the switch detection unit detects the switch. Storage means for storing the boom up / down angle at the time, when the detection result of the boom up / down angle detection means is not less than the stored boom up / down angle. When the detection result by the boom load detecting means exceeds the allowable boom load value due to the boom raising operation, the boom raising operation is stopped, and the boom lowering operation is allowed up to the stored boom raising / lowering angle. Overload protection device characterized.