JP4152626B2 - Overload prevention device for mobile crane - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an overload prevention device for a crane vehicle.
[0002]
[Prior art]
FIG. 3 shows a side view of a crane vehicle A that has a telescopic boom pivotally attached to a swivel base via a lever and is capable of changing the boom base fulcrum position of the telescopic boom during operation. The lower traveling body 2 has outriggers 3 on the front and rear sides thereof, and can be traveled by four wheels 1. The swivel base 4 is mounted on the lower traveling body 2 so as to be able to swivel, and the telescopic boom 6 is pivotally attached to the swivel base 4 via a lever 18 so as to be raised and lowered. Reference numeral 16 denotes a hoisting cylinder disposed below the telescopic boom 6. The crane vehicle A is in a posture at the time of traveling in which the telescopic boom 6 is fully reduced, the undulation angle is minimized, and the lower traveling body 2 is faced forward.
[0003]
One end 18a of the lever 18 is pivotally attached to the rear lower portion 4b of the swivel base 4 at a lever pivot point 12, and the other end 18b is swingable and fixed between a rear position and a front position. The hoisting cylinder 16 has its rod side end 16a pivoted to a support 17 on the lower surface of the telescopic boom 6 and its cylinder side end 16b pivoted to the swivel 4 at a hoisting cylinder pivot point 19. Yes. In the traveling posture of the crane car A, the hoisting cylinder 16 is supported by the hoisting cylinder receiver 20 provided in the front part 4a of the swivel base. Reference numeral 30 denotes a rear lever fixing portion, and reference numeral 31 denotes a front lever fixing portion. In the traveling posture, the lever 18 is fixed to the swivel base 4 by the rear lever fixing portion 30. The telescopic boom 6 has a base end portion 6b pivoted at a boom root fulcrum 14 of the lever other end portion 18b. The cab 5 is mounted on the swivel 4, and the traveling operation and crane operation of the crane vehicle A can be performed in the cab 5.
[0004]
FIG. 4 shows that the hoisting cylinder 16 is extended while the lever 18 is fixed to the swivel 4 by the rear lever fixing portion 30 from the traveling posture of the crane vehicle A in which the lever 18 is in the rear position. This shows the crane working posture in which In this working posture, the rear end turning radius R1 defined by the turning center S and the other end 18b of the lever is large, which is not suitable for crane work in a narrow place, but has high lifting stability during crane work. It will be a thing.
[0005]
FIG. 5 shows that the telescopic boom 6 is extended by extending the hoisting cylinder 16 after releasing the fixing of the lever 18 and the swivel 4 by the rear lever fixing portion 30 from the traveling posture of the crane truck A shown in FIG. The figure shows the posture when moving forward of the crane A and moving the other end 18b of the lever 18 forward while swinging around the lever pivot point 12.
[0006]
FIG. 6 shows the crane working posture of the crane vehicle A when the lever 18 is fixed to the swivel 4 by the front lever fixing portion 31 from the posture of FIG. 5 and then the hoisting cylinder 16 is extended and the telescopic boom 6 is raised and lowered. Is shown. In this crane work posture, the rear end turning radius R2 defined by the turning center S and the other end 18b of the lever is small, and the lifting stability during crane work is small, but the work is performed in a narrow place. It is suitable for.
[0007]
As described above, since the crane A described above changes the lifting performance according to the position of the lever 18, the overload prevention device needs to switch the lifting performance used for the control according to the position of the lever 18. It was.
[0008]
[Problems to be solved by the invention]
However, the conventional overload prevention device switches the lifting performance according to the lever position. After the operator confirms the lever position with his own eyes, the lever position input switch provided in the cab 5 inputs the lever position. As a result, the input error or forgetting to input may occur. If a lever position that is different from the actual lever position is input to the overload prevention device due to an incorrect input of the lever position or forgetting to input, the lifting performance corresponding to the lever position is not applied to the overload prevention device. For this reason, there is a risk that the crane vehicle will fall over due to a load exceeding the stability limit or the crane vehicle may be damaged due to a load exceeding the strength limit.
[0009]
Accordingly, the present invention seeks to solve the above-described problem by detecting the position of the lever with a detector and automatically switching the selection of the lifting performance in the overload prevention device based on the detection signal. is there.
[0010]
[Means for Solving the Problems]
The overload prevention device for a mobile crane described in claim 1 of the present application includes a swivel mounted on a lower traveling body having an outrigger so as to be able to turn, and can swing back and forth with respect to the swivel. A telescopic boom is pivotably mounted via a lever that can be fixed at a predetermined position on the base, and a hoisting cylinder is interposed between the telescopic boom and the swivel base, and is suspended by a rope suspended from the tip of the telescopic boom. An overload prevention device for a mobile crane for suspending a load, the overload prevention device comprising a load detector for detecting a suspended load and a lever position detector for detecting a fixed position of the lever with respect to a swivel And a boom length detector for detecting the boom length of the telescopic boom, a boom angle detector for detecting the boom angle of the telescopic boom, an overload prevention device main body, and an alarm stop device. , Further, the overload prevention device main body includes limit value calculating means for calculating a limit value in the telescopic boom posture at that time from the boom length, boom angle and lifting performance, and lifting performance storage means for storing the lifting performance. And a comparison means for comparing the suspended load with a limit value and outputting a signal corresponding to the result to the alarm stop device, and the lifting performance storage means stores a plurality of lifting performance according to the lever position. The limit value calculating means calculates the limit value based on the lifting performance according to the detection signal of the lever position detector.
[0011]
According to this configuration, the lever position detector detects the fixed position of the lever interposed between the swivel base and the telescopic boom base end with respect to the swivel base, and the detection signal is sent to the limit value calculation means of the overload prevention device. Therefore, the limit value calculation means of the overload prevention device calculates the limit value based on the lifting performance corresponding to the detection signal among the plurality of lifting performances corresponding to the lever position stored in the lifting performance storage means. It is. That is, the selection of the lifting performance in the overload prevention device can be automatically switched to the one corresponding to the lever position by the detection signal of the lever position detector.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In describing the embodiment of the present invention, an example in which the overload prevention device according to the present invention is applied to the mobile crane A shown and described in FIG. 3 in the prior art will be described. Accordingly, portions common to the present invention and those of the prior art will be described below using the same reference numerals and omitting detailed description.
[0013]
FIG. 1 shows a block diagram of an overload prevention device 50 according to an embodiment of the present invention.
[0014]
The overload prevention device 50 detects a load detector 51 for detecting a suspended load, a lever position detector 52 for detecting a fixed position of the lever 18 with respect to the swivel 4, and a boom length of the telescopic boom 6. A boom length detector 53, a boom angle detector 54 for detecting the boom angle of the telescopic boom 6, an overload prevention device main body 55, and an alarm stop device 56 are configured.
[0015]
As the load detector 51, the boom length detector 53, and the boom angle detector 54, those conventionally used in mobile cranes can be used. That is, the load detector 51 detects the axial force generated in the hoisting cylinder 16 by the suspended load suspended from the rope suspended from the distal end of the telescopic boom 6, and detects deformation of the shaft portion by a strain gauge. Or a device that detects the holding pressure of the oil chamber on the undulating cylinder holding side is used. As the boom length detector 53, a cord reel is arranged on the side surface of the base end boom of the telescopic boom 6, the tip of the cord to be fed is connected to the tip boom, and the amount of the cord fed is detected by a potentiometer. Is done. As the boom angle detector 54, one that is attached to the telescopic boom 6 and has a weight at the tip of a swingable lever and detects the swing angle of the lever with a potentiometer is used.
[0016]
The overload prevention device main body 55 includes a limit value calculation means 57 for calculating a limit value in the telescopic boom posture at that time from the boom length, boom angle and lifting performance, and a lifting performance storage means 58 for storing the lifting performance. Comparing means 59 for comparing the suspended load and the limit value and outputting a signal corresponding to the result to the alarm stop device 56 is constructed. The lifting performance storage means 58 stores the lifting performance that changes depending on the length and angle of the telescopic boom 6, and the overload prevention device 55 of the present application further has the number of fixed positions of the lever 18 relative to the swivel 4. The lifting performance corresponding to it is memorized. The overload prevention device main body 55 is configured by an electronic circuit including electronic components such as a known CPU, ROM, RAM, and the like, and is disposed inside the cab 5.
[0017]
The alarm stop device 56 includes alarm means arranged inside the cab 5 and stop means for stopping the operation of the crane vehicle A. Specifically, an alarm device that alerts the operator by voice or display when the load due to the suspended load reaches a predetermined value during crane work is used as the alarm means, and the actuator of the crane vehicle A is used as the stop means. An unload circuit or the like that is interposed in a driving hydraulic pressure supply circuit and that operates when a load caused by a suspended load reaches a predetermined value is used.
[0018]
FIG. 2 shows a specific example of the lever position detector 52. 2 is a cross-sectional view taken along the line BB in FIG. 3 and shows details of the rear lever fixing portion 30 and the lever pivot point 12. Since the sectional view is symmetrical, only the left half is shown in FIG. The swivel base 4 includes a base plate 32 and side plates 33 erected on the left and right sides of the base plate 32, and a boss 34 is fixed to the lower portion of the side plate 33 through the side plate 33. Reference numeral 36 denotes a pin fitted over the left and right bosses 34. The end of the pin 36 protrudes further outward from the side plate 33 from the boss 34, and a boss 37 provided on one end 18 a of the lever 18 is inserted in the protruding portion so as to be swingable. As described above, the lever pivot point 12 is constituted by the boss 34 on the side plate side, the boss 37 on the lever side, and the pin 36.
[0019]
Reference numeral 40 denotes a boss that penetrates and is fixed to the upper portion of the lever 18. A fixing pin 41 is housed inside the boss so as to be able to enter the side plate 33. The front end portion 42 of the fixing pin 41 is formed in a taper shape, and a connecting rod 43 projects outward from the swivel base 4 at the rear end portion. A fixed pin drive cylinder 44 is disposed between the connecting rod 43 and the lever 18 so that the fixed pin 41 can be plunged or pulled out toward the side plate 33 by expansion and contraction thereof.
[0020]
Reference numeral 45 denotes a boss fixed through the side plate 33. An inner surface 46 of the boss 45 is a tapered surface, and is configured to engage with the taper of the distal end portion 42 of the fixing pin 41. Therefore, when the front end portion 42 of the fixing pin 41 is projected toward the boss 45 of the side plate 33 by the fixing pin drive cylinder 44, the lever 18 is firmly fixed to the side plate 33, that is, the swivel base 4. Become. As described above, the rear lever fixing portion 30 described above is constituted by the boss 40 on the lever side, the fixing pin 41, the fixing pin drive cylinder 44, and the boss 45 on the side plate 33 side.
[0021]
A lever position detector 52 supports the proximity switch 60 with a support 61 so that the proximity switch 60 is arranged in the vicinity of the boss 45. As described above, when the lever 18 is fixed to the swivel base 4, the fixing pin 41 is plunged toward the boss 45 of the side plate 33 by the fixing pin drive cylinder 44. 42 is detected by the proximity switch 60, thereby detecting that the lever 18 is fixed at the fixed position.
[0022]
The lever position detector 52 in the front lever fixing portion 31 has the same configuration although not shown.
[0023]
The operation of the overload prevention device 50 described above is as follows. 4 or 6, the detection signal from the lever position detector 52 described above is output to the limit value calculation means 57 of the overload prevention device main body 55. Then, the lifting performance corresponding to the detection signal is automatically read from the lifting performance storage means 58. The boom length detector 53 and the boom angle detector 54 output boom length and boom angle signals to the limit value calculation means 57 of the overload prevention device main body 55. Then, the limit value calculating means 57 calculates the limit value based on the lifting performance corresponding to the detection signal of the lever position detector 52 and outputs the limit value to the comparing means 59. The comparison unit 59 compares the limit load value with the actual suspended load detected by the load detector 51, and alerts the alarm stop unit 56 when the load load has a predetermined relationship with the limit value. Outputs a stop signal. Then, the alarm means issues an alarm to the operator by voice or display, and the stop means stops the operation of the crane vehicle A.
[0024]
As described above, according to the overload prevention device 50 of the present invention, the lever position detector 52 determines the fixed position of the lever 18 interposed between the swivel base 4 and the telescopic boom base end portion 6b with respect to the swivel base 4. Since the detection signal is sent to the limit value calculation means 57 of the overload prevention device main body 55, the limit value calculation means 57 has a plurality of lifting performances corresponding to the lever positions stored in the lifting performance storage means 58. Of these, the limit value can be calculated based on the lifting performance according to the detection signal. That is, the selection of the lifting performance in the overload prevention device 50 can be automatically switched according to the lever position by the detection signal of the lever position detector 52.
[0025]
Of course, the overload prevention device 50 may be controlled in consideration of the turning angle. In that case, the lifting performance storage means 58 stores the lifting performance that changes depending on the turning angle in accordance with the outrigger extension state. Further, an outrigger extension state detector and a turning angle detector are added to the detector. In this case, in addition to the above-described control contents, when the detection signals of the outrigger extension state detector and the turning angle detector are output to the limit value calculation means 57, the lifting according to the outrigger extension state is performed. The performance is read out by the limit value calculating means 57, and the limit value taking into account the turning angle is calculated.
[0026]
Furthermore, the present invention is also applied to a crane vehicle in which an auxiliary jib can be attached to the front part of the telescopic boom 6, and during the auxiliary jib operation, the overload prevention device 50 responds to the detection signal of the lever position detector 52. Of course, the limit value may be calculated by automatically switching the jib lifting performance.
[0027]
In the above-described embodiment, the control of the overload prevention device 50 with respect to the forward stability and strength performance when the crane A hangs the suspended load has been described. Of course, the present invention can also be applied to the control of the rear stability. It is. That is, when the crane A lifts the telescopic boom 6 with the telescopic boom 6 directed to the side without installing the outrigger, the overload prevention device main body 55 has a predetermined hoisting angle because of its rear stability. Therefore, it is necessary to output an alarm stop signal to the alarm stop device 56, and the undulation angle at which the alarm stop signal should be output varies depending on the fixed position of the lever 18 with respect to the swivel 4. Therefore, the overload prevention is performed so that the undulation angle of the telescopic boom 6 that outputs an alarm stop signal in the rear stability control is automatically switched by a detection signal from the lever position detection device 52 to the overload prevention device main body 55. The apparatus main body 55 may be configured.
[0028]
【The invention's effect】
In the invention described in claim 1 of the present application, the lifting performance in the overload prevention device is automatically selected according to the lever position by the detection signal of the lever position detector. Since it can be switched to a switch, there is no possibility that an input error of the lever position or forgetting to input will occur. Therefore, it prevents the crane vehicle from falling over due to a load exceeding the stability limit, which is caused by a lever position different from the actual lever position being input to the overload prevention device, or damage to the crane vehicle due to a load exceeding the strength limit. It can be done.
[Brief description of the drawings]
FIG. 1 is a block diagram of an overload prevention apparatus according to an embodiment of the present invention.
FIG. 2 shows a specific example of a lever position detector 52. FIG.
FIG. 3 is a side view of a crane truck A.
FIG. 4 is a view showing a crane working posture.
FIG. 5 is a side view of a crane truck A in which a lever is swung forward.
FIG. 6 is a view showing a working posture of the crane truck A.
[Explanation of symbols]
1 is a wheel, 2 is a lower traveling body, 3 is an outrigger, 4 is a swivel, 5 is a cab, 6 is a telescopic boom, 12 is a lever pivot point, 14 is a boom fulcrum, 16 is a hoisting cylinder, and 17 is a support , 18 is a lever, 19 is a lifting cylinder pivot point, 20 is a lifting cylinder receiver, 30 is a rear lever fixing part, 31 is a front lever fixing part, 32 is a base plate, 33 is a side plate, 34 is a boss, 36 is a pin, 37 is a boss, 40 is a boss, 41 is a fixed pin, 42 is a tip, 44 is a fixed pin drive cylinder, 45 is a boss, 50 is an overload prevention device, 51 is a load detector, 52 is a lever position detector, 53 Is a boom length detector, 54 is a boom angle detector, 55 is an overload prevention device body, 56 is an alarm stop device, 57 is a limit value calculation means, 58 is a lifting performance storage means, 59 is a comparison means, and 60 is a proximity switch, 1 support

Claims (1)

A swivel base is mounted on a lower traveling body having an outrigger so as to be pivotable, and a telescopic boom can be raised and lowered via a lever that can swing back and forth with respect to the swivel base and can be fixed at a predetermined position of the swivel base. An overload prevention device for a mobile crane that interposes a hoisting cylinder between the telescopic boom and the swivel, and suspends a suspended load by a rope suspended from the distal end of the telescopic boom,
The overload prevention device includes a load detector that detects a suspended load, a lever position detector that detects a fixed position of the lever with respect to a swivel, and a boom length detector that detects a boom length of the telescopic boom. A boom angle detector that detects a boom angle of the telescopic boom, an overload prevention device main body, and an alarm stop device, and the overload prevention device main body includes the boom length and the boom angle. Limit value calculating means for calculating the limit value in the telescopic boom posture at that time, lifting performance storage means for storing the lifting performance, and a signal corresponding to the result of comparing the suspended load and the limit value Comparing means for outputting to the alarm stop device,
The lifting performance storage means stores a plurality of lifting performances according to the lever position, and the limit value calculating means calculates a limit value based on the lifting performance according to the detection signal of the lever position detector. A mobile crane overload prevention device.

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