JPS5952159B2 - Crane overload prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crane overload prevention device used to prevent truck cranes from overturning, booms from breaking, etc.
In particular, the present invention aims to provide a crane overload prevention device that simplifies the overall structure of the device and is highly accurate.

Various methods have been proposed and put into practical use as overload prevention devices for truck cranes.

In commonly used devices, the limit value of the lifting load value is set based on conditions such as the length of the crane boom and the angle of the boom, and the set limit lifting load value and the load value of the actually lifted load are set. It is common that the actual load value exceeds a limit value, and a warning is issued in case of overturning or breakage.

For this reason, in conventional equipment, several curves expressing the relationship between the boom's heave angle and the limit value of the lifting load are stored in the storage means, using the length of the boom as a parameter, and when the load is being lifted, The limit lifting load value is read from the storage means based on the condition of the boom, that is, the length and the angle of elevation, and the read limit value and the actual load value are compared and calculated.

The storage means uses the length of the boom as a parameter to store the relationship between the heave angle and the limit value of the lifting load as a graph, or directly calculates the three-dimensional calculation of the heave angle, length, and lifting load, so it has a relatively large capacity. For example, read-only memory is used.

However, when measuring the weight of a load lifted by a crane, it is troublesome to simply detect the lifting load from the tension of the wire due to the problem of slinging of the hook part that lifts the load.

Therefore, as another means, for example, the stress applied to the hydraulic cylinder that changes the boom's heave angle is measured, the moment applied to the boom is directly measured, and this measured value is compared with the limit value from the storage means. .

Therefore, there is a drawback that the device becomes complicated and expensive.

However, in the case of a truck crane, when the boom is extended out in front of the truck, that is, when it is suspended from the front, the center of gravity of the truck itself is located at the front, making it easy to topple over.

For this reason, the limit value for overturning differs depending on whether the boom is facing forward or protruding backwards or laterally.

Therefore, the limit value read out from the storage means must be corrected depending on the direction of the boom, which has the disadvantage that the device becomes increasingly complex.

An object of the present invention is to provide a crane overload prevention device that is simple in construction and highly reliable.

In this invention, load detectors are installed on a plurality of outriggers, for example, four, that a truck crane has.The load on the outriggers is detected, and the center of gravity position is calculated by combining the load values detected from each detector. A fall prevention device configured to display whether or not the center of gravity is within a rectangular area with four outriggers as vertices, and to issue an alarm when the center of gravity approaches the line of this rectangle. It is.

In addition, as a boom breakage prevention device, for example, a load detector is attached to each stage of the boom to directly detect the load applied to the boom, and the ratio of the load value to the boom's mechanical strength limit can be determined. It is configured so that it can be displayed.

Alternatively, instead of attaching a stress detector to each stage of the boom, attach only one stress detector to the bottom boom (base boom), and calculate the limit value from this stress value and the number of boom stages currently in use. It is also possible to store it in advance and display and warn the limit due to mechanical strength.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a side view of the truck crane lifting a load, and FIG. 2 shows a plan view thereof.

In the figure, numeral 1 indicates the truck body. This truck body 1 usually has four outriggers 2a, 2b, 2C92d.
is installed, and when operating the crane, use outrigger 2.
a, 2b, 2C, and 2d are jutted out laterally as shown in FIG. 2, and their legs are extended so that the truck body 1 is floated and supported by the outriggers 2a to 2d.

Further, the truck body 1 is provided with a turning base 3.

A crane boom 4 is attached to this rotating base 3.

The boom 4 is configured such that its luffing angle θ can be changed by a luffing hydraulic cylinder 5.

In this example, the boom 4 shows a case in which three stages of booms 4a, 4b, and 4C are extendable and retractable, and in the retracted state, the other booms 4b and 40 are stored in the lowermost boom 4a.

In a tropical example, there is an additional jib 4d at the top of the top boom 4C.
A wire 6 is paid out from the tip of the jib 4d, and a hook 7 attached to the tip of the wire 6 is used to lift a load 8.

In some cases, a wire 9 is let out from the uppermost end 4C of the telescopic boom and the load is lifted by a hook 7' attached to the tip of the wire 9.

Up to this point, the structure is exactly the same as a conventional truck crane.

In this invention, the outriggers 2a and 2b described above
, install a load detector on each outrigger 2a, 2C, 2d,
Detect the load applied to 2b, 2C, and 2d.

The load detectors attached to the outriggers 1 to 2a to 2d can be constructed by, for example, attaching a helen gauge directly to any of the members that make up each outrigger, or by attaching a load detector called a load cell to each leg. can be configured.

The load values detected by each load detector are supplied to an arithmetic circuit to calculate the center of gravity positions for the four outriggers 2a, 2b, 2C, and 2d.

An example is shown in FIG.

In FIG. 3, lla, llb, 11C, and lld indicate load detectors attached to each of the ara I/rigs 2a to 2d, and the detected load values of these load detectors 11a to 11d are supplied to the arithmetic circuit 12 for calculation. The center of gravity position is calculated by combining the detected load values in the circuit 12, and the center of gravity position is displayed on the display 13.

For example, a cathode ray tube can be used as the display 13.

On the tube surface of the cathode ray tube, draw the positions of the riggers 2a to 2d to the rear 1 as shown in Figure 4, draw a frame 14 at the 90% position where the outriggers 2a to 2d will fall, and at the 100% position. Draw frame 15.

Reference numeral 16 indicates a bright spot for displaying the center of gravity position calculated by the calculation circuit 12 and displayed by a signal obtained by the calculation.

Therefore, as long as the bright spot 16 is inside the frames 14 and 15, there is no fear of the lifted load falling over regardless of the load value, and when the bright spot 16 approaches the frame 14 drawn inside, the alarm shown in FIG. The stop signal generator 17 can issue a warning, and the outer frame 15 can be configured to represent a tipping limit.

Also, a signal to stop the crane can be sent simultaneously with the alarm.

On the other hand, the present invention also provides a breakage prevention device for the boom 4.

For example, one method is to
and load detectors 18a, 18b such as I-range gauges, respectively, on the jib 4d.

Install 18C and 18d, boom 4a to 4C and jib 4
Depending on the usage situation of d, the detection value of the load detector of the weakest part, that is, the load detector installed on the boom or jib used at the top stage, is compared with the limit load value of that part, for example, the limit is calculated. What percentage is the detected value, assuming the value is 100%?
For example, calculate the value corresponding to 19 in Figure 4.
It can be displayed on a part of the tube surface of the cathode ray tube 13 as shown in FIG.

As to which detected value from among the load detectors 18a to 18d is selected, for example, the detected value of the load detector attached to the uppermost boom of the currently used boom is selected.

For this purpose, as shown in FIG. 3, the switch 21 may be switched by the boom stage number switching signal transmitter 20 to select the detected value of the load detector at the top stage and supply it to the arithmetic circuit 12.

Each boom 4a to 4C and jib 4d are connected to the calculation circuit 12 in advance.
It is assumed that the limit value of the mechanical strength of the selected boom is stored, and the limit value of the selected boom is read out in conjunction with switching of the switch 2 and is calculated and processed together with the detected value. I can do it.

In this way, by constantly displaying the percentage of the load applied to the highest boom or jib in use at that time of the limit value of that boom or jib, the highest The safety value for the strength limit of the weak portion is displayed, and it is guaranteed that no boom breakage accident will occur unless the displayed value exceeds 100% in this state.

As another method of the boom breakage prevention device, for example, a load detector is provided only on the lowest boom 18a of the booms, and the detected value from this load detector is used to calculate the load applied to the highest boom or jib depending on the number of boom extension/retraction stages. It may also be possible to calculate and display what percentage of the mechanical strength limit value of the uppermost boom or jib the converted load value corresponds to.

Still another method is to always subtract the weight of the truck body 1 and the crane from the load values detected by the outriggers 2a to 2d, and calculate the actual load of the load from the load value that increases when the load is lifted. The load value applied to the uppermost boom in use is calculated from the actual load value, and the calculated value is calculated as a percentage of the mechanical strength limit of the uppermost boom.
It is also conceivable to calculate whether it corresponds to , and display it.

In any of the above breakage prevention methods, when the load value applied to each boom approaches the limit value of the mechanical strength of each boom, an alarm is issued from the alarm and stop signal generator 17,
The ability to be configured to stop the crane together with this is similar to the case of the fall prevention device described above.

As explained above, according to the present invention, as an overturn prevention device, if the center of gravity deviates outward from at least the outer frame 15 connecting the fulcrum, the number of telescopic steps of the boom and the boom angle θ
Alternatively, it is clear that the boom will not fall over regardless of the direction of the boom, and a highly reliable display can be performed.

Also, the display is easy to understand and convenient.

However, since there is no need to store the tipping limit curve, a large-capacity storage means can be omitted.

Furthermore, since there is no need to detect the number of stages of boom extension, boom angle θ, boom direction, etc., the apparatus can be greatly simplified.

Furthermore, the boom breakage prevention device calculates the load value applied to the boom by actual measurement or calculation, and displays the percentage of the load value relative to the limit value of each boom, so this case also works. The display is easy to understand and convenient.

Also, regardless of whether the overturning prevention device or the boom breakage prevention device is used, when the limit value is approached, the alarm and stop signal generator 17 will issue an alarm and a crane stop signal, so there is no risk of an actual overturning or breakage accident. It has the advantage of being highly reliable and safe to use.

Although the above description has been made assuming that there are four outriggers, it is easy to understand that the number may be at least three and is not necessarily limited to four.

[Brief explanation of the drawing]

FIG. 1 is a side view for explaining the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a system diagram showing an example of essential parts of the device according to the present invention, and FIG. 4 is a display of the device according to the present invention. It is a front view showing an example. 1 Nidrac main body, 2a, 2b, 2C, 2d: Outrigger, lla, llb, IIC, lld: Load detector attached to outrigger, 12: Computing unit, 19: Tolerance to withstand the limit of mechanical strength according to the number of boom stages An indicator that displays values.

Claims (1)

[Claims] 1. A stress detector attached to each of a plurality of outriggers of a truck crane, and a stress detector based on the stress detector. A calculator that calculates the center of gravity position of a truck crane based on input, a display that displays the calculation results, a load detector attached to each boom of the crane, and a limit value of the mechanical strength of each boom that is stored in advance. and an arithmetic unit that compares and calculates the detected load value and a mechanical strength limit value, and displays on a part of the display the ratio of the allowable value to the mechanical strength limit according to the number of stages. Crane overload prevention device.