JPH0367957B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for a crane with a hoistable jib mounted on a boom.

In a crane equipped with a jib, the boom and jib are assembled and placed on the same plane as the crane body, and after the boom and jib are installed in a usable state as a crane, work is performed using the boom or jib. The operation of installing the device in a ready-to-use state will be explained in more detail with reference to FIGS. 1 and 2.

FIG. 1 is a side view of the schematic configuration of the crane.
In the figure, 1 is a crane main body, 2 is a boom, 3 is a jib provided on the boom 2 so that it can be hoisted, 4 is a boom hoisting drum provided on the crane main body 1, and 5 is a jib hoist that is also provided on the crane main body 1. Drum, 6 is a rope for hanging loads provided on the boom 2, 7
is a hanging load rope provided on the jib 3.

FIG. 2 is a side view of the general structure of the crane showing the process of making the boom and jib ready for use. In the figure, the same parts as those shown in FIG. 1 are given the same reference numerals. A shows a posture in which the boom 2 and the jib 3 are assembled and placed on the ground (on the plane where the crane body 1 exists). To put the boom 2 and jib 3 in a usable state, that is, in a working position,
First, from posture A, raise the boom 2 while bringing the jib 3 into contact with the ground. Therefore, boom 2 and jib 3 rise simultaneously, and boom 2 and jib 3
When the angle β formed by the jib becomes the angle β ₁ , the undulating drum 5 of the jib 3 is fixed. This state is shown as posture B.
Next, raise the boom 2 from posture B. In this case, the angle β between the boom 2 and the jib 3 does not change,
The angle β remains ₁ . When the boom angle α reaches the angle α ₁ , the hoisting drum 4 of the boom 2 is fixed. This state is shown as posture C. From posture C, jib 3 is now raised to posture D. This posture D is within the normal working range of the crane. Depending on the working conditions such as the position of the load at that time, the crane operation may be carried out by driving the boom 2 and lifting the load with the load rope 6, or by driving the jib 3 and lifting the load with the load rope 7. It will be carried out by hanging.

By the way, as mentioned above, boom 2 and jib 3
In the process of raising the boom 2 from posture A, the boom 2
The tip of the jib 3 must be kept in contact with the ground until the angle β between the jib 3 and the jib 3 reaches a certain predetermined angle, that is, the angle β ₁ described above. This condition is imposed by taking into account the stability of the crane, the hoisting device, the strength of the boom, etc. If the boom is raised without meeting these conditions, excessive force will be applied to the boom hoisting rope. This may cause accidents such as the crane falling over or being damaged. That is, when trying to raise the boom 2 without touching the tip of the jib 3, a moment due to the weight of both the boom 2 and the jib 3 is applied to the boom hoisting rope, but in the state of attitude A shown in Fig. 2, the moment is not applied to the boom hoisting rope. becomes excessive,
There is a risk of the crane falling over or being damaged. Therefore, by grounding the tip of the jib 3, the moment due to the weight of the jib 3 is reduced, and the boom 2 can be erected. Furthermore, when the state of posture B is reached and the sum of the moments due to the dead weight of boom 2 and jib 3 falls within a predetermined tolerance (as the moment arm decreases), jib 3 is fixed (i.e., jib 3 is It becomes possible to raise the boom 2 by lifting the tip of the boom 2. At this time, the angle β ₁ formed by the boom 2 and the jib 3 becomes a certain predetermined angle setting value. It was extremely difficult to do so, and there was a risk of misidentification, erroneous operation, or failure to confirm, leading to the above-mentioned accident.

The present invention was made in view of the above circumstances, and its purpose is to solve the above-mentioned conventional problems and prevent accidents such as falls and damage during crane installation operations, without placing any burden on the operator. There are crane safety devices that can prevent this.

In order to achieve this objective, the present invention detects the boom angle to the ground and the jib angle to the ground, calculates the angle between the boom and the jib from these boom to the ground angle and the jib angle to the ground, and the calculated angle is set in advance at the tip of the jib. Based on the detected angle of the boom to the ground, it is determined whether the angle between the boom and the jib has been exceeded, which is set in advance, on the condition that the boom can be raised by fixing the ups and downs of the jib from the state where the jib is grounded. The height of the jib foot is calculated based on the detected jib angle from the ground, and the vertical projection of the jib is calculated based on the detected jib angle to the ground. When the angle formed by the jib and the jib exceeds a set angle and the difference is greater than or equal to the set height, a danger instruction signal is output that activates an alarm device, display device, stop device, etc. .

Hereinafter, the present invention will be explained based on illustrated embodiments.

First, prior to explaining the configuration of this embodiment, the operations used in this embodiment will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a diagram showing the dimensions and angles of the crane with the tip of the jib in contact with the ground. In the figure, 2
a is the center (boom foot) of a coupling pin that couples the boom 2 to the crane body 1; 2b is the boom tip position (boom point). 3a is the center (jib foot) of a connecting pin that connects the jib 3 to the boom 2. 3b is the jib tip position (jib point), which is in the grounded state in the illustrated case. A line connecting the boom foot 2a and the boom point 2b indicates the boom center line, and its dimension L indicates the boom length. A line connecting the jib foot 3a and the jib point 3b indicates the jib center line, and its dimension l indicates the jib length. Also, boom point 2b and jib foot 3a
The line connecting is a perpendicular line drawn from the jib foot 3a to the boom center line, and the distance is E. Note that the boom point 2b is a virtual point defined as described above. h is the height from the ground to the boom foot 2a, A ₁ is the boom angle, A ₂ is the jib angle, and β is the angle between the boom 2 and the jib 3. Note that the boom angle A ₁ is a positive value in the illustrated state, and the jib angle A ₂ is a negative value in the illustrated state.

Here, the ground height of the jib foot 3a is H ₁ ,
The height H ₁ is determined based on the boom angle A ₁ using the following formula.

H ₁ =L·sinA ₁ −E·cosA ₁ +h (1) Moreover, the vertical projection distance H ₂ of the jib length l can be determined by the following equation.

H ₂ =l・sinA ₂ (2) Figure 4 is a diagram showing the dimensions and angle of the crane when the tip of the jib is off the ground. In the figure, the same parts as in FIG. 3 are given the same reference numerals. The height H ₁ determined by the above formula (1) and the projection distance H ₂ determined by the above formula (2) are equal when the jib tip is in contact with the ground, and H ₁ =H ₂ . but,
As shown in Figure 4, when the tip of the jib is lifted off the ground, H ₁ > H ₂ . Therefore, to determine whether the tip of the jib is in contact with the ground, calculate the difference between height H ₁ and height H ₂ (H ₁ - H ₂ ), and the value is 0 (it is in contact with the ground). This can be judged by whether there is a difference (floating).

On the other hand, the angle β between the boom 2 and the jib 3 can be determined from the boom angle A ₁ and the jib angle A ₂ using the following equation.

β=π−(A ₁ −A ₂ ) …(3) From the above, when raising the boom 2 from posture A, in order to determine whether a dangerous situation has occurred, (3) Calculate the equation to determine the angle β as the angle β ₁
In the state in which the height difference (H ₁ - H 2 ) has not been reached (β > β ₁ ), check whether the value of the height difference (H 1 - H ₂ ) is less than a certain allowable limit value (this value is defined as ΔH). All they have to do is to compare, and if the value of the difference (H ₁ - H ₂ ) is greater than or equal to the value ΔH, it can be determined that the situation is in danger.
Here, the value ΔH may theoretically be approximately 0, but it is set to a value that will not cause erroneous judgments even if the calculated values of the heights H ₁ and H ₂ fluctuate somewhat due to vibrations of the boom or jib, etc. Therefore, the configuration of this embodiment for making such a determination is shown in FIG.

FIG. 5 is a block diagram of a crane safety device according to an embodiment of the present invention. In the figure, 10 is the boom angle
Boom angle detector that detects A ₁ , 11 is jib angle A ₂
This is a jib angle detector that detects. 12 is a cosine function generator that outputs a cosine value according to the input angle signal; 13, 14 are sine function generators that output a sine value according to the input angle signal; 15, 16, 17;
1 is a multiplier, 18 and 19 are adders and subtracters, 20 is a subtracter, 21 and 22 are comparators that compare the input signal and a set value, and 23 is an AND gate circuit. 24 is
This is an alarm circuit activated by the output signal of the AND gate circuit 23.

Next, the operation of this embodiment will be explained. A cosine function generator 12 takes the boom angle signal A ₁ detected by the boom angle detector 10 and generates a signal cosA ₁ .
The multiplier 15 adds to this signal cosA ₁ a signal E corresponding to the distance between the boom point 2b and the jib foot 3a.
, and outputs the signal E・cosA ₁ . Further, the sine function generator 13 takes in the boom angle signal A ₁ and generates a signal sinA ₁ , and the multiplier 16 generates a signal sinA ₁ using the boom angle signal A 1 .
is multiplied by the signal L corresponding to the boom length to obtain the signal L・
Outputs sinA ₁ . The adder/subtracter 18 is the multiplier 15,
16 output signal and a signal h corresponding to the height of the boom foot 2a, (L・sinA ₁ −E・
cosA ₁ +h). Therefore, the output of the adder/subtractor 18 becomes a signal _H1 corresponding to the height determined by equation (1). Further, the sine function generator 14 takes in the jib angle signal A ₂ detected by the jib angle detector 11 and generates a signal sinA ₂ , and the multiplier 17 adds a signal l corresponding to the jib length to this signal sinA ₂ . Multiply the signal l・sinA ₂ and output it. This output signal l・
sinA ₂ becomes a signal H ₂ corresponding to the projection distance determined by equation (2). The subtracter 20 inputs the output signal H ₁ of the adder/subtractor 18 and the output signal H ₂ of the multiplier 17, and outputs a difference signal (H ₁ −H ₂ ) between the two. Comparator 2
1 compares this difference signal (H ₁ - _{H 2} ) with the set value signal ΔH corresponding to the permissible limit value, and outputs a high level only when the signal (H ₁ - _{H 2} ) is greater than or equal to the signal ΔH. Output a signal.

On the other hand, the adder/subtractor 19 inputs the boom angle signal A ₁ , the jib angle signal A ₂ , and the signal π corresponding to an angle of 180°, calculates (π−A ₁ +A ₂ ), and calculates the result using equation (3). A signal β corresponding to the angle formed by the boom 2 and the jib 3 is output. The comparator 22 compares this signal β with the signal β ₁ corresponding to the angle β ₁ and outputs a high level signal only when the signal β is larger than the signal β ₁ .

The AND gate circuit 23 inputs the signals from the comparators 21 and 22, and outputs a high level signal when both signals are at high level. That is, the AND gate circuit 23 outputs a high level signal when the angle β between the boom 2 and the jib 3 is larger than the angle β ₁ and the tip of the jib is floating at a height of ΔH or more. is a danger signal that indicates danger. This danger instruction signal activates the alarm circuit 24 to issue an alarm to notify the driver of the danger and prevent accidents.

Note that an automatic stop circuit that automatically stops the crane or a display circuit that displays the type of danger may be used instead of the alarm circuit. Alternatively, a combination of these can also be used.

Thus, in this embodiment, the height of the jib foot and the vertical direction of the jib are determined based on the values detected by the boom angle detector and the jib angle detector, the boom length, the jib length, and the distance between the boom point and the jib foot. Calculate the difference in projection distance in the direction and the angle formed by the boom and jib, and if the difference is a height greater than the set value,
In addition, a danger signal is output when the angle exceeds the set value, so that the operator can check the boom angle, jib angle, ground contact status of the jib tip, etc. in the process of setting up the crane in a usable state. It is possible to prevent the crane from falling over or being damaged without checking. Additionally, cranes are generally required to be equipped with an overload prevention device, and in this case, an angle detector is attached, so the boom angle detector and jib angle detector can be used together.

Note that the calculation section in the above embodiment can be configured by a microcomputer, and in this case, if the crane is equipped with an overload prevention device using a microcomputer, the function of the calculation section can be implemented by the overload prevention device. It can also be included in a microcomputer. Furthermore, since the danger signal is not required within the normal working range (posture D shown in Figure 2), it is not possible to configure the danger signal to be output only when the boom angle _A1 is below a certain value. Of course.

As described above, the present invention detects the boom angle and the jib angle, calculates the angle between the boom and the jib from these values, and outputs a signal when the value exceeds a set value. , calculate the difference between the height of the jib foot and the vertical projection distance of the jib, output a signal when the difference is greater than a set value, and output a danger signal when these two signals are output at the same time. Therefore, accidents such as overturning and damage during crane installation operations can be prevented without placing any burden on the operator.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the general structure of the crane, Fig. 2 is a side view of the schematic structure of the crane showing the process of making the boom and jib ready for use, and Figs. 3 and 4 show the dimensions and angle of the crane. Line diagram shown, 5th
The figure is a block diagram of a crane safety device according to an embodiment of the present invention. 10... Boom angle detector, 11... Jib angle detector, 12... Cosine function generator, 13, 14... Sine function generator, 15, 16, 17... Multiplier, 1
8, 19...addition/subtraction device, 20...subtraction device, 21,
22... Comparator, 23... AND gate circuit.

Claims (1)

[Claims] 1. In a crane having a boom and a hoistable jib attached to the boom, a boom angle detection device for detecting a boom angle from the ground, a jib angle detection device for detecting a jib angle from the ground, and an angle formed by the boom and the jib. and a value obtained by the first calculation means that can fix the ups and downs of the jib and raise the boom from a state where the tip of the jib is in contact with the ground. a first comparison means that outputs a signal when a preset angle between the boom and the jib is exceeded; and a second calculation means that calculates the height of the jib foot based on a detected value of the boom angle detection device. and a third calculation means for calculating a projected distance in the vertical direction of the jib based on the detected value of the jib angle detection device, and a difference between the values obtained by the second calculation means and the third calculation means. a second comparison means that outputs a signal when the height is equal to or greater than a certain predetermined height setting value, the first comparison means and the second comparison means;
A safety device for a crane, comprising output means for outputting a danger instruction signal when signals are simultaneously output from the comparison means.