JP2001220086A - Load cell, and crane overturn alarming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the alarming accuracy of an overturn alarming device by detecting the low load of an outrigger with high accuracy. SOLUTION: This crane overturn alarming device comprises a load cell 1 which comprises a coil spring 5 having a strain gage 4, and an upper load cell case 6 and a lower load cell case 7 which holds the coil spring 5 from the top and the bottom thereof to transmit the load of the outrigger to the coil spring 5, and is provided with support parts 8, 9 to support the load exceeding a predetermined value to restrict the deflection of the coil spring 5 between the upper load cell case 6 and the lower load cell case 7, and an alarm unit to give the overturn alarm based on the detected load of the outrigger from the load cell 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load cell capable of withstanding a maximum load of an outrigger of a crane and capable of measuring a low load with high accuracy, and a crane falling alarm device using the load cell.

[0002]

2. Description of the Related Art Generally, a vehicle-mounted crane in which a crane is mounted on a vehicle is provided with an outrigger, and when the crane is operated, the outrigger is extended and grounded to ensure stability. However, if the suspended load or the working radius is excessive, the balance may be lost and the crane may fall.

Therefore, in order to prevent a fall accident, the grounding load of the outrigger is always detected during work, and the detected load is set to a specified value (usually arbitrarily set in a range of 0 to 3000 N).
In the following cases, a crane overturn prevention device that determines that the outrigger is in a floating state and issues an alarm is used. Conventionally, as a means for detecting a ground load of an outrigger of a crane overturn prevention device, there are a means for detecting an internal pressure of an outrigger cylinder and a means for detecting a ground load using a load cell.

However, in the detection of the internal pressure of the outrigger cylinder, the frictional resistance of the outrigger cylinder packing is large, and the accuracy of the detected value is questionable. In the case of detecting a grounding load using a load cell, detection accuracy is high when detecting a high load such as when the outrigger is in a maximum load state, but extremely high when detecting a floating state of the outrigger. The detection accuracy when detecting low load was poor.

[0005] That is, a load cell generally used is selected according to the magnitude of the maximum measured load, and the limit load (load resistance) of the load cell is typically about 1.5 times the maximum measured load. Normally, in the case of detecting the load of the outrigger, since the maximum load is about 90000N, a load cell having a limit load of about 135000N must be used.

However, as shown in FIG. 20, when a load cell having a limit load of about 135000 N and a load of 0 to 3000 N is measured, the output value of the load cell becomes a very small output of about 2% of the maximum output value. Therefore, accurate load detection has been difficult in view of the measurement error of the load cell itself.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem in the crane overturn alarm device, and can withstand the maximum load of the outrigger of the crane and detect a low load with high accuracy. It is an object to provide a simple load cell and a fall alarm device.

[0008]

The load cell of the present invention comprises:
A load cell comprising a coil spring provided with a strain gauge, and an upper load cell case and a lower load cell case for vertically sandwiching the coil spring and transmitting the load of the outrigger to the coil spring, when a load equal to or more than a predetermined value is applied. A supporting portion for supporting the load and suppressing the deflection of the coil spring is provided between the upper load cell case and the lower load cell case.

In this load cell, when the load of the outrigger exceeds a predetermined value, the supporting portion supports the load in place of the coil spring, so that a load cell having a large withstand load and a small maximum measured load can be selected. The detection accuracy at low load is high and the cost is low. This load cell is mounted on the outrigger of the crane, and the fall alarm device of the crane of the present invention in which a fall alarm is issued based on the load detection value of the load cell can be manufactured at low cost and can issue a fall alarm with high accuracy. The safety of the crane can be improved.

If the load cell is vertically movable within the outrigger cylinder of the crane and the upper load cell case is mounted on the outer box of the outrigger via a pin, the load cell can be easily mounted. If the load cell is configured in a float shape and the upper load cell case is attached to the outrigger cylinder via a pin, it may be attached instead of the conventional float,
Installation of the load cell is further simplified.

A crane tipping alarm device in which a load cell is integrated with an alarm unit so as to be installed under the float of an outrigger and issues a tipping alarm based on the load detection value of the load cell is provided before the crane operation is started. It can be placed under the outrigger cylinder and stored in the storage place after the crane operation is completed. Since it is not incorporated in the outrigger itself, it can be applied to all cranes and has versatility.

When the load cell and the alarm section of the fall alarm device can be arranged separately from each other, a radio transmitter for transmitting a load detection signal to the load cell side and a radio receiver for receiving the load detection signal on the alarm section side are provided. In a crane operated by an operator at a distance from the outrigger, the operator can more reliably recognize the overturn warning.

[0013]

FIG. 1 is a front view showing a state in which a load cell according to an embodiment of the present invention is mounted on an outrigger of a crane, FIG. 2 is a plan view of the load cell, and FIG. 3 is AA in FIG. FIG. 4 is an explanatory diagram of a load measurement range of the load cell. The load cell 1 is interposed between the upper end of the outrigger cylinder 12 and the upper plate 11 for mounting the outrigger cylinder 12 at the outer end of the outrigger 2 of the vehicle-mounted crane. It is attached by suspending it with bolts 13.

Accordingly, the load cell 1 receives a load acting on the outrigger 2 when the outrigger cylinder 12 extends and the float 14 at the lower end touches the ground, so that the load on the outrigger 2 can be detected. This load cell 1
Is composed of a coil spring 5 to which a strain gauge 4 is attached, an upper load cell case 6 and a lower load cell case 7 which vertically sandwich the coil spring 5 and transmit the load of the outrigger 2 to the coil spring 5. The upper load cell case 6 and the lower load cell case 7 are disk-shaped,
Supporting portions 8 and 9 are formed on the peripheral portion so as to surround the coil spring 5 held at the center.
Further, a bolt hole 10 through which the mounting bolt 13 is inserted is formed in the peripheral portion. Here, the support portions 8 and 9 are formed integrally with both the upper load cell case 6 and the lower load cell case 7. However, the support portions 8 and 9 may be formed on only one of the upper load cell case 6 and the lower load cell case 6. 7 may be provided separately.

The support portion 8 on the upper load cell case 6 side and the support portion 9 on the lower load cell case 7 side
Is set so that a predetermined gap D is formed when is a free length. When the load of the outrigger 4 acts on the coil spring 3 via the upper load cell case 5 and the lower load cell case 6, the coil spring 3 is compressed and gradually bends. 9
Are in contact with each other to support the load and restrain the bending of the coil spring 3. Therefore, as shown in FIG. 4, the output of the load cell 1 increases linearly until the load reaches a predetermined value (3000 N), and the output does not increase any more even if a load higher than the predetermined value acts. Becomes

The measurement range in which the load increases linearly is from 0 to 3000 N here, but can be set arbitrarily by changing the spring constant of the coil spring 5 and the gap D. The output of the load cell 1 is sent via a cable 15 to an alarm unit (not shown). When the crane is at risk of falling, the load on the outrigger 2 on the opposite side to the falling direction decreases to a value near 0N. Therefore, the alarm unit
An overturn alarm is issued based on the load detection value of the outrigger 2 from the load cell 1. For the alarm, any means such as an alarm, an alarm lamp, an alarm display on a display, an alarm message by voice, and the like can be used alone or in combination.

The detected load value from the load cell 1 is 0 to 3
Since it can output linearly in the range of 000N,
Judgment is made between a warning state that does not lead to an immediate fall but requires caution in operation and an imminent danger state that immediately leads to a fall, and an alarm is issued in multiple stages to prevent a fall accident. Safe operation can be performed so as to prevent

When a load equal to or more than a predetermined value acts, the support portions 8 and 9 come into contact with each other to support the load.
The load cell 1 having a small maximum measured load can be used, and a low load can be detected with high accuracy. As a specific system configuration, for example, the outrigger cylinder 12 is extended, the float 14 is grounded,
When the load acting on the outrigger 2 reaches 3000 N, the first switch for self-holding the power to the alarm unit is turned on, and the audible alarm to notify the alarm is sounded for 5 seconds. The first switch is provided on the load cell 1 so as to mechanically detect, for example, that the gap D between the support portion 8 on the upper load cell case 6 side and the support portion 9 on the lower load cell case 7 becomes zero. Keep it.

During the operation of the crane, the alarm unit operates the outrigger 2
When the load becomes 1500 N or less, an intermittent sound is made, and when the load becomes 500 N or less, a continuous sound is emitted to give an alarm. When the crane work is completed and the outrigger cylinder 12 is contracted to store the outrigger 2, the load on the outrigger 2 becomes 0 N, so that a continuous sound is produced. In this case, the power supply self-holding circuit is cut off. The second switch can be turned off manually or a timer or the like can be used to turn off the second switch after 10 seconds, for example.

FIG. 5 is an explanatory view showing a state in which a load cell is mounted on an outrigger of a crane according to another embodiment of the present invention.
6 is a sectional view taken along the line BB of FIG. 5, FIG. 7 is an enlarged view of the load cell portion of FIG. 5, FIG. 8 is a sectional view taken along the line CC of FIG. 7, and FIGS. FIG. 4 is an explanatory diagram of a state where a load acts on a load cell and a coil spring is bent.

The basic configuration of the load cell 31 is shown in FIG.
, A coil spring 35 having a strain gauge 34 attached thereto, an upper load cell case 36 and a lower load cell case 3 for vertically sandwiching the coil spring 35 and transmitting the load of the outrigger 2 to the coil spring 35.
7. The upper load cell case 6 and the lower load cell case 7 have a rectangular parallelepiped shape, and two coil springs 35 are disposed in front and back. Support portions 38 and 39 are formed so as to surround the coil springs 35. I have. The number of coil springs 35 can be appropriately selected according to the maximum load to be measured.

The upper load cell case 36 and the lower load cell case 37 are connected by connecting bolts 40 so that a predetermined gap D is formed between the support portions 38 and 39 when the coil spring 35 has a free length. The lower load cell case 37 is connected to the connecting bolt 4 in the bending direction of the coil spring 35.
It can move freely with respect to 0. A pin hole 41 for mounting is formed in an upper portion of the upper load cell case 36.

The outrigger cylinder 12 contained in the inner box 42 of the outrigger 2 is
The upper load cell case 36 is mounted on the outer box 45 of the outrigger 2 by inserting a pin 44 into a pin hole 41 of the upper load cell case 36 in a vertically movable manner within a load cell chamber 43 provided at an upper portion of the outer cell 45. Therefore, when the outrigger cylinder 12 is contracted, as shown in FIG.
It is suspended from the pins 44 via the upper load cell case 36, and the coil spring 35 has a free length, so that a gap is formed between the support portions 38 and 39.

When the outrigger cylinder 12 expands and the float 14 at the lower end touches the ground, the load cell 31 receives a load acting on the outrigger 2, and the coil spring 35 is compressed and bent, so that the load on the outrigger 2 can be detected. it can. When a load of a predetermined value acts, the support portions 38 and 39 come into contact with each other to support the load, as shown in FIG.

The output of the load cell 31 is sent to an alarm unit (not shown) via the cable 15, and the alarm unit outputs the load cell 31.
A fall warning is issued based on the detected load value of the outrigger 2 from. Here, the load cell 31 is incorporated in the load cell chamber 43 of the outrigger cylinder 12 in advance,
Since it can be mounted simply by inserting the pin 44 into the pin hole 41 from the outside of the outer box 45 of the outrigger 2, the mounting is easier than when interposed between the outrigger cylinder 12 and the upper plate 11 as shown in FIG. It is.

FIG. 11 is an explanatory view showing a load cell mounted on an outrigger of a crane according to still another embodiment of the present invention, FIG. 12 is a sectional view taken along line EE of FIG. 11, and FIG. 13 is a load cell of FIG. FIG. 14 is an enlarged view of a portion of FIG.
FIGS. 15 and 16 are cross-sectional views of the load cell serving as the float of the outrigger, and FIG. 15 and FIG. 16 are diagrams illustrating the state where the load spring acts on the load cell and the coil spring is bent.

The basic structure of the load cell 51 is as shown in FIG.
A coil spring 55 to which a strain gauge 54 is attached, an upper load cell case 56 and a lower load cell case 5 which sandwich the coil spring 55 up and down to transmit the load of the outrigger 2 to the coil spring 55
7. The load cell 51 has a floating outer shape, and two coil springs 55 are disposed between the upper load cell case 6 and the lower load cell case 7 in the front and rear directions. 58 and 59 are formed.

The upper load cell case 56 and the lower load cell case 57 are connected so that a predetermined gap D is formed between the support portions 58 and 59 when the coil spring 55 has a free length, and is connected by connecting bolts 60. The lower load cell case 57 is connected to the connecting bolt 6 in the bending direction of the coil spring 55.
It can move freely with respect to 0. A pin hole 61 for mounting is formed in an upper portion of the upper load cell case 56.

The outrigger cylinder 12 housed in the inner box 42 of the outrigger 2 is attached to the outer box 45 of the outrigger 2 with a pin 62 at the top. The load cell 51 is provided with a pin hole 61 of the upper load cell case 56.
By inserting the pin 64 through the outrigger cylinder 1
It is attached to the lower end of 2 so as to act as a float.

Therefore, when the outrigger cylinder 12 is contracted, as shown in FIG.
, The coil spring 55 has a free length, and a gap is formed between the support portions 58 and 59. When the outrigger cylinder 12 is extended, the load cell 51 is grounded as a float and receives a load acting on the outrigger 2. Therefore, since the coil spring 55 is compressed and bent, the load on the outrigger 2 can be detected. When a load of a predetermined value acts, as shown in FIG.
8 and 59 come into contact with each other to support the load, thereby suppressing the bending of the coil spring 55.

The output of the load cell 51 is sent to an alarm unit (not shown) via the cable 15, and the alarm unit outputs the load cell 51.
A fall warning is issued based on the detected load value of the outrigger 2 from. The load cell 51 is configured in a float shape, and can be attached to the outrigger cylinder 12 instead of the conventional float simply by inserting the pin 64 into the pin hole 61 of the upper load cell case 56, so that attachment is further simplified. Become.

FIG. 17 is a front view showing a use state of a crane fall alarm device according to still another embodiment of the present invention, FIG. 18 is a plan view of the crane fall alarm device, and FIG. 19 is FIG. FIG. 7 is a sectional view taken along line GG of FIG. In the fall alarm device 20, the load cell 1 and the alarm unit 21 are integrally formed.

That is, a load cell 1 similar to that shown in FIGS. 1 to 4 is provided at the center of a portable box 23 having a handle 22 on the front surface, and an alarm unit 21 comprising a buzzer 24 and a control unit 25 is provided on the right side thereof. A battery 26 is placed on the left side as a power source,
The upper surface of 3 is covered with a floor plate 27 so that only the upper load cell case 6 of the load cell 1 projects. A dust seal 28 is provided between the floor plate 27 and the upper load cell case 6. On the front of the alarm unit 21, there is provided a second switch 2 for manually turning off the self-holding circuit of the power supply at the end of the work.
9 are provided.

When the fall alarm device 20 is placed under the float 14 of the outrigger 2 as shown in FIG. 17 and the outrigger cylinder 12 is extended, the load on the outrigger 2 acts. Works similarly. Therefore, the fall alarm device 20 may be placed under the outrigger cylinder 12 before the start of the crane operation, and stored in a storage location after the crane operation is completed.
Since it is not built into itself, it can be applied to all cranes and has versatility.

When the crane work is performed on soft ground, an iron plate or the like is laid under the outrigger 2 to increase the ground contact area so that the outrigger 2 does not sink. The device 20 can be used instead of an iron plate in such a case. Even when the ground is not soft, the stability is improved by using the overturn warning device 20.

The load cell 1 of the fall alarm device 20 and the alarm unit 21 are divided so that they can be arranged separately from each other.
If a wireless transmitter (not shown) for transmitting a load detection signal is provided on the side, and a wireless receiver (not shown) for receiving the load detection signal is provided on the alarm unit 21 side, for example, an alarm may be issued from the operation unit of the crane. In a remote-controlled crane or the like operated by an operator at a distance from the outrigger 2, the operator can more reliably recognize the overturn warning. Further, the operation of the crane can be automatically stopped before the fall.

[0037]

As described above, the load cell of the present invention has a large load resistance, a low load detection accuracy, and is inexpensive. In addition, the fall warning device for a crane according to the present invention can be manufactured at a low cost and can issue a fall warning with high accuracy, thereby improving safety. If the load cell is provided in the outrigger cylinder of the crane so as to be movable up and down by a predetermined distance, and the upper load cell case is attached to the outer box of the outrigger via a pin, the load cell can be easily attached.

If the load cell is configured in a float shape and the upper load cell case is mounted on the outrigger cylinder via a pin, it may be mounted instead of the conventional float, and the mounting of the load cell is further simplified. The crane's fall warning device, which is configured so that the load cell can be installed under the float of the outrigger integrally with the alarm unit and issues a fall warning based on the load detection value of the load cell, requires the It is only necessary to put it down and store it in the storage place after the crane operation is completed. Since it is not incorporated in the outrigger itself, it can be applied to all cranes and has versatility.

When the load cell and the alarm unit of the fall alarm device can be arranged separately from each other, a radio transmitter for transmitting a load detection signal to the load cell side and a radio receiver for receiving the load detection signal on the alarm unit are provided. In a crane operated by an operator at a distance from the outrigger, the operator can more reliably recognize the overturn warning.

[Brief description of the drawings]

FIG. 1 is a front view showing a state in which a load cell according to an embodiment of the present invention is attached to an outrigger of a crane.

FIG. 2 is a plan view of a load cell.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an explanatory diagram of a load measurement range of a load cell.

FIG. 5 is an explanatory view showing a state in which a load cell according to another embodiment of the present invention is attached to an outrigger of a crane.

FIG. 6 is a sectional view taken along line BB of FIG. 5;

FIG. 7 is an enlarged view of a load cell part of FIG. 5;

FIG. 8 is a sectional view taken along line CC of FIG. 7;

FIG. 9 is an explanatory diagram illustrating a state in which the float of the outrigger is grounded, a load acts on the load cell, and the coil spring is bent.

FIG. 10 is an explanatory view showing a state in which a float of an outrigger is grounded, a load acts on a load cell, and a coil spring is bent.

FIG. 11 is an explanatory view of a state in which a load cell is mounted on an outrigger of a crane according to still another embodiment of the present invention.

FIG. 12 is a sectional view taken along line EE of FIG. 11;

FIG. 13 is an enlarged view of a load cell part of FIG. 11;

FIG. 14 is a sectional view taken along line FF of FIG. 13;

FIG. 15 is an explanatory diagram illustrating a state where a load cell serving as a float of an outrigger is grounded, a load acts on the load cell, and a coil spring is bent.

FIG. 16 is an explanatory view showing a state where a load cell serving as a float of an outrigger is grounded, a load acts on the load cell, and a coil spring is bent.

FIG. 17 is a front view showing a use state of a crane fall warning device according to still another embodiment of the present invention.

FIG. 18 is a plan view of a crane fall warning device.

FIG. 19 is a sectional view taken along line GG of FIG. 18;

FIG. 20 is an explanatory diagram of a load measurement range of a conventional load cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Load cell 2 Outrigger 4 Strain gauge 5 Coil spring 6 Upper load cell case 7 Lower load cell case 8 Support part 9 Support part 10 Bolt hole 11 Upper plate 12 Outrigger cylinder 13 Bolt 14 Float 15 Cable 20 Fall alarm 21 Alarm part 22 Handle 23 Box Reference Signs List 24 buzzer 25 control unit 26 battery 27 floor plate 28 dust seal 29 second switch 31 load cell 34 strain gauge 35 coil spring 36 upper load cell case 37 lower load cell case 38 support unit 39 support unit 40 connecting bolt 41 pin hole 42 inner box 43 load cell chamber 44 Pin 45 Outer box 51 Load cell 54 Strain gauge 55 Coil spring 56 Upper load cell case 57 Lower load cell case 58 Support section 59 Support section 61 Hole 62 pin 64 pin D gap

Claims (6)

[Claims] A coil spring provided with a strain gauge;
A load cell comprising an upper load cell case and a lower load cell case that sandwiches a coil spring vertically and transmits the load of an outrigger to the coil spring. The load cell supports a load when a load equal to or more than a predetermined value is applied, and flexes the coil spring. A load cell, wherein a support portion for stopping the load cell is provided between the upper load cell case and the lower load cell case. 2. A crane fall warning device for a crane, wherein the load cell according to claim 1 is attached to an outrigger of the crane, and a fall warning is issued based on a detected load value of the load cell. 3. A crane overturn alarm according to claim 2, wherein the load cell is provided in the outrigger cylinder of the crane so as to be vertically movable by a predetermined distance, and the upper load cell case is attached to an outer box of the outrigger via a pin. apparatus. 4. The crane falling warning device according to claim 2, wherein the load cell is configured in a float shape, and the upper load cell case is attached to the outrigger cylinder via a pin. 5. A crane overturn alarm device according to claim 1, wherein the load cell according to claim 1 is integrated with an alarm section so as to be installed under the float of the outrigger, and a fall alarm is issued based on a load detection value of the load cell. 6. A radio transmitter for transmitting a load detection signal to the load cell side, and receiving a load detection signal to the alarm unit side, wherein the load cell and the alarm unit of the fall alarm device according to claim 5 can be arranged separately. A crane overturn warning device comprising a radio receiver.