JPH0138753B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a jib work overload prevention device.

(Description of the prior art and its problems) A jib is an attachment that is attached to the tip of a telescopic boom type boom in order to hoist a load as high as possible. The jib itself is made to be lightweight and long according to the requirements. For this reason, the jib does not necessarily have great structural strength.
Therefore, when a jib is attached to the tip of a telescoping boom and a load is lifted at the tip of the jib (hereinafter referred to as jib work), the rated load at the tip of the jib is determined by the bending strength of the jib in most cases. ing.

On the other hand, when a predetermined load is suspended from the tip of the jib, the bending force generated on the jib due to the load varies depending on the hoisting angle of the jib, that is, the hoisting angle of the telescopic boom to which the jib is attached. It does not change depending on the In other words, in most cases, the rated load at the tip of the jib during jib work is
It does not vary depending on the length of the boom.

By the way, the following devices have been conventionally used as overload prevention devices for jib work to ensure safety during jib work.

One of them, as shown in Japanese Patent Application Laid-Open No. 59-27260, is to use an overload prevention device during jib work to detect the actual moment (based on the load acting on the boom hoisting cylinder) generated around the hoisting fulcrum of a telescoping boom. The moment component due to the self-weight of the boom and jib (calculated as a function of the self-weight of the boom and jib, which is a constant, the boom heave angle, and the boom length) is subtracted from the actual lifting load, that is, the moment component due to the actual lifting load. The lifting load moment generated by the upper load around the boom hoisting fulcrum is determined, and the actual lifting load is calculated by dividing this lifting load moment by the working radius of the crane. The rated load during jib work obtained as a function of angle is compared, and a signal is issued to stop the crane or give an alarm based on the comparison result.

Here, it is noted that the rated load at the jib tip is determined by the boom's luffing angle within a predetermined working radius (above a predetermined boom luffing angle); is calculated as a function only of the heave angle of the boom, thereby simplifying the means for outputting the limit value to be compared with the actual value.

However, the method described above, which calculates the jib tip lifting load from the actual moment generated around the boom's hoisting fulcrum and compares it with the jib tip rated load, calculates the moment component due to the self weight of the boom and jib from the actual moment. The purpose is to compare the lifting load at the tip of the jib, which is calculated by excluding There was a problem that an alarm or a signal to stop the crane was outputted unnecessarily. In other words, if the actual moment generated around the boom's heave fulcrum changes due to wind acting on the boom or boom swinging, which has little effect on the jib strength, the lifting load will be converted by the amount of change in the actual moment. As a result of the value being directly added to the jib tip lifting load, there is a problem in that an alarm or stop signal is often issued even if the actual jib tip lifting load is within the jib rated load.

In addition, as another conventional technology, the critical moment around the boom hoisting fulcrum during jib work is memorized and output for each boom hoisting angle and each boom length, and this output value is compared with the actual moment. Depending on the result, an alarm is issued or the movement of the crane is stopped. In this case, even if the moment actually changes due to swinging of the boom or wind acting on the boom, this fluctuation will be reflected in the suspended load and The moment is relatively small compared to the moment based on the dead weight of the boom and jib, and therefore, the disadvantage of issuing an alarm or a signal to stop the movement of the crane more than necessary as in the conventional example can be avoided. However, it is necessary to store and output the critical moment itself for each boom length as well as for each boom lifting angle, which has the disadvantage of requiring a huge storage capacity.

The present invention is an attempt to solve the problems of the prior art as described above, and is aimed at unnecessarily raising or lowering alarms even if the actual moment acting on the boom changes due to swinging of the boom or wind acting on the boom. In order to avoid outputting a signal to stop the movement of the crane, this method adopts the latter prior art method mentioned above, which compares the actual moment generated around the boom's lifting fulcrum with the critical moment, but the critical moment is The storage capacity of the output means for outputting can be reduced. It is an object of the present invention to provide a jib work overload prevention device.

(Means for Solving the Problems) In order to solve the problems of the prior art described above, the present invention is configured as follows.

A jib work overload prevention device used in a crane device in which a jib is attached to the tip of a telescoping boom that can be raised and retracted to handle a suspended load at the tip of the jib, and the device includes a boom hoisting angle detection means and a boom length detection means. , an actual moment detection means for outputting an actual moment response value generated around the boom's lifting fulcrum;
A limit moment output means for outputting a limit moment response value as a function of boom heave angle and boom length, and when the output of the former reaches the output of the latter, an alarm is issued or the movement of the crane is stopped, The limit moment output means is
A jib tip rated load signal that stores a jib tip rated load response signal as a function of the boom heave angle and uses the actual boom heave angle signal as an input signal to output a jib tip rated load response signal corresponding to the boom heave angle at that time. an output section, a jib working radius output section that outputs a jib tip working radius signal based on the actual boom heave angle signal and boom length signal, and a jib tip rated load signal output section and a jib working radius output section that output signals from the jib tip rated load signal output section and the jib working radius output section. The rated load moment response value calculation unit calculates the moment generated around the boom hoisting fulcrum by the rated load at the tip of the jib based on the rated load moment response value calculation unit, which receives the boom hoisting angle signal from the boom hoisting angle detection and the boom length signal from the boom length detection unit. A boom/jib dead weight moment response value output unit that calculates the moment generated around the boom hoisting fulcrum by the boom dead weight and the jib dead weight as a function of these two signals, and the output of the rated load moment response value calculation unit and the boom/jib dead weight A jib work overload prevention device comprising: a limit moment response value calculation section that adds the outputs of the dead weight moment response value output section and outputs a limit moment response value.

(Function) The overload prevention device for jib work of the present invention configured as described above compares the actual moment and the limit moment, so it is possible to avoid unnecessary overload prevention due to moment fluctuations caused by swinging of the boom or wind. A limit moment response value output means that does not generate an alarm or a signal to stop the movement of the crane, and outputs a limit moment compared to an actual moment, requires only a very small amount of storage capacity for each of its output sections. Since this memorized value is used to calculate the critical moment around the boom's heave fulcrum, the storage capacity is significantly greater than when the critical moment itself is stored for each boom angle and length. It can be reduced to

(Examples) The present invention will be described below based on Examples. In Figure 1, B is the boom, J is the jib, and C is the boom B.
A undulation cylinder that undulates, R is a swivel base,
In this example, the jib J is a two-stage telescoping type, and the tilt angle (the angle at which the boom B axis and the jib J axis intersect when the jib J is attached to the tip of the boom B) is changed in two stages. We are equipped with what we can. (Note: Therefore, this jib J has four types of rated performance as shown in Figure 2 depending on the contraction and extension of the second stage jib part J ₂ and the shallow and deep tilt angles. In Fig. 2, the rated load at the tip of the jib for each of these four types of jib work modes is displayed on coordinates with the rated load at the tip of the jib on the vertical axis and the undulation angle of the boom B on the horizontal axis. ) FIG. 3 is a block diagram of the present invention. 1, 2,
3 is a known actual moment detection means, boom hoisting angle detection means, and boom length detection means, which respectively detect the actual moment (moment in the overturning direction) around the boom hoisting fulcrum pin, the hoisting angle θ, and the boom length L.
outputs a corresponding electrical signal.

The limit moment output means is as follows. 5
is a jib tip rated load signal output unit that stores the jib tip rated load response signal for each hoisting angle of the boom B in the above-mentioned four types of jib work modes, and is composed of generators for each of the functions 51 to 54. has been done. Reference numeral 6 is a boom/jib self-weight moment response value output unit, which stores the total self-weight moment of the jib and boom in the above-mentioned four types of jib work modes.
It is composed of four function generators. Note that this total self-weight moment memory value corresponds only to the length of the boom from the most contracted state to the most extended state at a boom heave angle of 0°, so this value is stored as a percentage for each boom/jib self-weight. A simple structure of the moment response value output section is sufficient. Furthermore, it should be noted that each function generator 51 to 5
4, 61 to 64, if the working mode of the jib is one or two types, it goes without saying that one or two pieces are sufficient. Reference numerals 4 and 13 indicate switches for automatically or manually selecting the corresponding function generators 51 to 54 and 61 to 64 according to four types of jib work modes. The switches 4 and 13 are interlocked so that when one is operated, the other will follow suit. For this reason, the jib tip rated load output section 5
When outputting the jib end rated load signal response value in a specific jib working state, the boom/jib dead weight moment response value output unit 6 outputs the boom/jib dead weight moment response value in the specific jib working state. It's becoming like that.

The jib end rated load response signal output section 5 is connected to the switch 4
The selected function generator outputs an electric signal corresponding to the rated load W at the tip of the jib to the rated load moment response value calculation section 10.

On the other hand, the function generator 7 receives the electric signal corresponding to the heave angle θ from the boom heave angle detection means 2.
Multipliers 9 and 12 convert it into an electrical signal corresponding to cosθ.
Output towards. Further, the adder 8 takes in the electric signal corresponding to the boom length L from the boom length detection means 3 and adds the jib length Lj (L+
Lj) is output to the multiplier 9. Here, the multiplier 9 calculates the working radius R by calculating {(L+Lj)×cosθ} based on each electric signal received, and outputs an electric signal corresponding to this to the rated load moment response value calculation unit 10. do. The function generator 7, adder 8, and multiplier 9 constitute a jib working radius signal output section that outputs a working radius signal R at the tip of the jib based on an actual boom heave angle signal and a boom length signal. The rated load moment response value calculation unit 10 receives this electric signal R and also receives the electric signal W from the jib tip rated load signal output unit 5, and calculates (W×R), that is, the jib tip rated load W and the working radius R. A moment (a moment generated by the rated load at the tip of the jib around the boom hoisting fulcrum) is calculated, and an electric signal corresponding to this is output to the limit moment response value calculation section 11.

On the other hand, the multiplier 12 receives an electric signal corresponding to the total dead weight moment Mb of the boom and jib (the value at the boom's heave angle of 0° (described above)) from the function generator group 6, and also receives it from the function generator 7. Calculate (Mb×cosθ) using the electric signal (cosθ), that is, determine the boom/jib self-weight moment response value Mo when the boom is raised, and output an electric signal corresponding to this to the limit moment response value calculation unit 11. do. The function generator group 6 and the multiplier 12 are
Configures the jib dead weight moment response value output section. Here, the limit moment response value calculation section 11 receives the electrical signal (W) from the rated load moment response value calculation section 10.
×R) and the electric signal (Mo) from the boom/jib self-weight moment response value output section (multiplier 12) and calculate {(W×R)+Mo}, that is, the rated load at the tip of the jib is calculated around the boom hoisting fulcrum. Calculate the critical moment response value Me, which is the sum of the moment generated by the boom and the moment generated around the boom hoisting fulcrum by the boom's own weight and the jib's own weight.

When the limit moment response value Me is calculated in this way, it is compared in the comparator 14 with an electric signal corresponding to the actual moment response value M around the boom hoisting fulcrum from the actual moment detection means 1, and the actual moment response value M is a certain percentage of the critical moment response value Me, for example 90% or 100
%, an alarm signal is output.

(effect) Next, the effects of the present invention will be explained.

The present invention grasps the actual moment around the load boom hoisting fulcrum acting on the jib due to the suspended load and compares it with the limit moment. Unnecessary alarms or signals to stop the movement of the crane will not be issued.

In addition, the present invention calculates the critical moment compared to the actual moment based on the boom/jib self-weight moment of the boom and jib and the rated load memory value of the jib.
Since the limit moment corresponding to the boom length and boom hoisting angle is calculated at certain times during work, the limit value is lower than the conventional method in which the limit moment is stored for each boom hoisting angle and each boom length. can significantly reduce the amount of memory required.

In the above embodiment, the jib is a two-stage telescoping type and the tilt angle can be changed in two stages, and the jib work overload prevention device of the present invention is adopted. Of course, the work overload prevention device can be used in a device where the jib does not extend or contract and the tilt angle does not change.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of the crane device according to the present invention, Figure 2 is a diagram showing the performance characteristics of the jib, and Figure 3 is a diagram showing the performance characteristics of the jib.
The figure is a block diagram of the present invention.

Claims (1)

[Claims] 1. An overload prevention device for jib work used in crane equipment in which a jib is attached to the tip of a telescoping boom that can be raised and retracted to handle suspended loads at the tip of the jib, which includes a means for detecting the boom raising and lowering angle, and a boom length. The former comprises a detection means, an actual moment detection means for outputting an actual moment response value generated around the boom heave fulcrum, and a limit moment output means for outputting a limit moment response value as a function of the boom heave angle and the boom length; When the output of the boom reaches the latter output, an alarm is issued or the movement of the crane is stopped. A jib tip rated load signal output section receives the boom heave angle signal as an input signal and outputs a jib tip rated load response signal corresponding to the boom heave angle at that time. A jib working radius signal output section that outputs a working radius signal, and a moment generated around the boom hoisting fulcrum by the rated load at the jib tip is calculated based on signals from the jib tip rated load signal output section and the jib working radius signal output section. The rated load moment response value calculation unit receives the boom heave angle signal from the boom heave angle detector and the boom length signal from the boom length detector, and calculates the boom weight and jib weight around the boom hoisting fulcrum as a function of these two signals. Boom/jib self-weight moment response value output unit that calculates the generated moment;
and a limit moment response value calculation section that adds the output of the rated load moment response value calculation section and the output of the boom/jib self-weight moment response value output section and outputs a limit moment response value. jib work overload prevention device.