JP3543439B2 - Forklift eccentric load detector - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an unbalanced load detection device for a forklift for detecting an eccentric load in the left-right direction when a load is loaded on a fork, that is, a shift amount of the center of gravity of the load relative to the center between the left and right forks.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a forklift provided with a device for detecting an unbalanced load of luggage loaded on a fork, for example, Japanese Patent Laid-Open No. 5-147896 is known. In the forklift described in this publication, load sensors for detecting loads are respectively installed between left and right forks and an upper fork bar on which the upper hooks of the forks are locked. The left and right load sensors detect a downward load applied to the left and right forks, and input a detection signal corresponding to the load to the microcomputer. The microcomputer calculates the amount of deviation from the center between the forks in the position of the center of gravity of the load lifted based on the two detection signals, and displays the result on a display to inform the operator.
[0003]
By the way, in the case of a container to be unloaded by a fork, as shown in the schematic diagram of FIG. 8, the load is loaded in the container W in a right or left direction, and the center of gravity of the container W is shifted from the container center (PP line). , Four fork pockets A to D (two on each side) are set. That is, the container is normally unloaded using the left and right inner pockets B and C, and when the center of gravity is shifted from the center of the container and the amount of the shift exceeds a predetermined value, if it is on the left side, After increasing the distance between the forks 7 from L to L1, use the left outside pocket A and the right inside pocket C, and if it is the right side, use the left inside pocket B and the right outside pocket D to handle the container. To do. Accordingly, a forklift handling such a type of container W is provided with a fork moving device for adjusting the spacing of the forks 7 or an adjustment of the spacing of the forks 7 and a side shift (moving the forks in the left-right direction while keeping the fork spacing constant). And a fork moving device capable of performing both.
[0004]
[Problems to be solved by the invention]
In the case of a forklift equipped with the unbalanced load detection device described in the above-mentioned publication, the load applied to the fork is directly detected by a load sensor interposed between the upper hook of the fork and the upper fork bar. It has the advantages of accurate and reliable detection. However, on the other hand, at the time of adjusting the distance between the forks 7, the load sensor slides on the upper surface of the fork bar while receiving the load of the fork even if the adjustment is performed in an empty state. However, there is a problem that the load sensor is easily damaged. Therefore, the above-described unbalanced load detection device is difficult to apply to a forklift in which a fork moves with respect to a fork bar, that is, a forklift provided with a fork moving device or a side shift device.
[0005]
The present invention has been made in view of the above-described problems, and an object of the present invention is to prevent a load sensor from being relatively displaced with respect to a pressing member when a fork is moved, so that load detection can be accurately performed. Another object of the present invention is to provide an offset load detecting device that can protect a load sensor while taking advantage of the advantage of the above.
[0006]
[Means for Solving the Problems]
To solve the above problems, the present invention takes the following measures.
That is, the invention of claim 1 is:
Left and right forks are movably mounted along the upper and lower fork bars, and the forklift bias load detecting device includes a load detector for detecting a load applied between the left and right forks and the lower fork bar. And
The load detector includes a load sensor capable of detecting a load applied between the fork and the lower fork bar, and a pressing member that applies the load to the load sensor.
The load sensor is installed on the fork with a pressure receiving surface of the load sensor facing the lower fork bar,
The pressure member is provided movably in the front-rear direction with respect to the fork, and a roller bracket that abuts a pressure receiving surface of the load sensor, and is rotatably supported by the roller bracket and provided on a front surface of the lower fork bar. And a roller abutting so as to be able to roll.
[0007]
According to the first aspect of the present invention, the rearward loads applied to the left and right forks are detected by the load sensors via the pressing members.
Also, when brought into lateral movement along the fork to the fork bars, rollers of the pressure member provided in the fork that roll along the front of the lower fork bars, corresponding to the lateral movement of the fork. At this time, the load sensor and the roller bracket of the pressing member are laterally moved integrally with the fork while maintaining the contact state.
Further, since the roller of the pressing member rolls along the front surface of the lower fork bar, the movement resistance of the fork can be reduced.
[0008]
The invention of claim 2 is
An unbalanced load detection device for a forklift according to claim 1,
On the fork, install a box that opens the rear surface,
The load sensor is fitted and accommodated in the box, and the roller bracket is fitted so as to be movable in the front-rear direction .
[0009]
According to the second aspect of the invention having such a configuration, the load sensor and the roller bracket are assembled by being fitted into a box installed on the fork.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. First, a cargo handling device with a fork moving device provided on the front side of a forklift will be described based on the front view of FIG. 1 and the side view of FIG. As shown in the figure, upper and lower fork bars 3 and 4 are fixed to the front surface of a lift bracket 2 that moves up and down along a mast 1 erected at the front of the vehicle body. Alternatively, left and right fork shafts 5 each formed of a cylindrical body are provided horizontally via a shaft bracket 6. The left and right forks 7 disposed on the front surfaces of the upper and lower fork bars 3 and 4 have a boss 7a at the upper end of the upright end supported by the fork shaft 5 so as to be slidable and rotatable back and forth. Is locked to the lower fork bar 4 via the lower hook 7b, and unnecessary forward rotation displacement is regulated.
[0013]
Between the upper and lower fork bars 3, 4, two shift cylinders 8 for moving the fork 7 in the left-right direction are vertically arranged in parallel. The shift cylinder 8 has a base end connected to the upper fork bar 3 and a rod end connected to the one fork 7. The other shift cylinder 8 has a base end connected to the lower fork bar 4 and a rod end connected to the other fork 7.
[0014]
Next, the present invention is applied to a forklift equipped with a cargo handling device with a fork moving device configured as described above, and the center between the left and right forks when a load, for example, a container W shown in FIG. An eccentric load detection device that detects the amount of deviation of the position of the center of gravity of the container W from the center of the fork) will be described with reference to FIGS. The unbalanced load detection device is roughly divided into a load detection unit 10 for detecting loads applied to the left and right forks 7, a microcomputer 16 mounted on the vehicle body, and a lift 16 mounted on the front side of the driver's seat and lifted by the left and right forks 7. And a display device 19 provided with a center-of-gravity position display unit for displaying the load imbalanced state of the loaded luggage.
[0015]
The load detectors 10 are respectively installed at the lower portions of the left and right forks 7, and they are housed in the box 11 having a substantially rectangular shape that opens only the rear surface joined to the lower inner surface of the fork 7 by welding. The load sensor 12 includes a load sensor 12 for detecting a load applied to the fork 7, a roller 13 as a pressing member and a roller bracket 14 interposed between the load sensor 12 and the front surface of the lower fork bar 4.
[0016]
The roller bracket 14 is formed in a substantially U-shape in a side view, and the rollers 13 are disposed on upper and lower horizontal pieces 14 a and are rotatably supported via pins 15. The roller bracket 14 is fitted to the box 11 so as to be movable in the front-rear direction so that at least the rear end of the roller 13 abutting on the front surface of the lower fork bar 4 is exposed from the box opening. The portion 14b is abutted against the pressure receiving surface of the load sensor 12 in the box 11 from behind.
[0017]
That is, when a load is loaded on the fork 7, the load sensor 12 is pressed by the backward load applied to the fork 7 via the roller 13 and the roller bracket 14 interposed between the fork 7 and the fork bar 4. The load applied to the fork 7 is detected.
[0018]
FIG. 6 is a block diagram showing the electrical configuration of the eccentric load detecting device. The microcomputer 16 temporarily stores a CPU, a read-only memory (ROM) storing various control programs and various data, and a calculation result of the CPU. And a rewritable memory (RAM). The left and right load sensors 12 are connected to the input side of the microcomputer 16 via input interfaces 17 and 18, and the microcomputer 16 detects the detection signals output from both load sensors 12, that is, the backward direction applied to the fork 7. After inputting detection signals corresponding to the pressing force due to the load, the amount of deviation of the center of gravity of the lifted luggage from the center of the fork is calculated based on the two detection signals.
[0019]
A display device 19 is connected to the output side of the microcomputer 16. The microcomputer 16 calculates the amount of shift of the center of gravity and outputs a corresponding display signal to the center of gravity display unit of the display device 19. Has become. When the signal corresponding to the shift amount is input, the barycentric position display unit moves the bar indicating the center of gravity position to the side (right or left) to which a large load is applied from the reference position, and corresponds to the shift amount. It moves and displays as much as you do.
[0020]
The eccentric load detection device according to this embodiment is configured as described above. Therefore, for example, when the fork 7 is inserted into the pockets B and C of the container W shown in FIG. The backward load applied to the load 7 is detected by the left and right load sensors 12, and a detection signal corresponding to the load is input to the microcomputer 16. Then, the microcomputer 16 calculates a shift amount of the center of gravity corresponding to the weight of the container W based on the two detection signals, and outputs a display signal of the shift amount to the center-of-gravity position display unit of the display device 19. Based on this, a bar indicating the position of the center of gravity is displayed on the center of gravity display.
[0021]
Therefore, if it is determined that the bar is within the allowable range of any amount that will not interfere with transportation, the worker will continue loading and unloading the container, and if it is judged that the bar is out of the allowable range, suspend the work temporarily. I do. When the position of the center of gravity exceeds the allowable range of the shift amount, the fork 7 is pulled out from the pockets B and C of the container W, and then the shift cylinder 8 is operated to widen the interval between the left and right forks 7. The cargo handling operation is restarted using the pocket on the side shifted in position. That is, when the center of gravity is shifted to the left, the left outer pocket A and the right inner pocket C are used. When the center of gravity is shifted to the right, the right outer pocket B and the left inner pocket are used. The cargo handling operation is performed using the pocket D. As a result, if it is determined that the position of the center of gravity is within the allowable range, the operation is continued, and if it is determined that the position is still beyond the allowable range, the operation is stopped.
[0022]
Therefore, according to this unbalanced load detecting device, the state of unbalanced load when the fork 7 lifts the luggage can be easily confirmed by visual observation, so that the cargo handling operation is performed while the center of gravity of the luggage is displaced so as to hinder transportation. Is prevented.
[0023]
Now, in this embodiment, the load applied to the fork 7 is directly detected by the load sensor 12, so that the load applied to the fork bars 3, 4 and the lift bracket 2 supporting the fork 7 is indirectly detected. In this case, the load can be detected more accurately than in the conventional method, and a highly reliable load detector can be obtained. Further, when the fork 7 is moved laterally to the left or right for the purpose of adjusting the interval or the side shift, the roller bracket 14 moves with its upright piece 14b in contact with the pressure receiving surface of the load sensor 12. That is, since a structure which does not cause relative displacement so-called sliding between the roller bracket 14 of the member for pressurizing it and load sensor 12, can prevent damage to the load sensor 12.
[0024]
In addition, the load detection unit accommodates the load sensor 12, the roller 13, and the roller bracket 14 in a box 11 provided on the side surface of the fork 7, and the roller 13 comes into contact with the front surface of the lower fork bar 4. Even if they are simply fitted without a fixing work such as tightening, there is no danger that they will fall out of the box 11, and the assembling work is greatly simplified.
[0025]
The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the invention. For example, as shown in FIG. 7, the load detecting unit 10 holds the load sensor 12 with a retainer 20 fixed to a lower side surface of the fork 7 and an arm unit 14c that protrudes the roller bracket 14 of the roller 13 upward. May be changed to a structure in which the pin 21 is supported in a suspended manner by the pins 21 so as to be pivotable back and forth . The fork 7 may be slidably locked to the upper fork bar 3 via an upper hook. Furthermore, in the embodiment, the load detector 10 is provided on the inner surface of the fork 7, but may be set on the outer surface.
[0026]
【The invention's effect】
As described in detail above, according to the first aspect of the invention, the load applied to the fork is directly detected to secure the advantage that load detection is accurate and highly reliable, and then the fork is moved laterally. When applied to a forklift of the type described above, it is possible to effectively prevent the load sensor from being damaged by eliminating sliding between the load sensor and the roller bracket of the pressing member that directly presses the load sensor.
Further, since the rollers of the pressing member roll along the front surface of the lower fork bar, the fork can be moved smoothly in the lateral direction.
[0027]
According to the second aspect of the present invention, since the load sensor and the roller bracket, which are constituent members of the load detecting unit, can be assembled simply by fitting them into the box, the assembling work can be simplified.

[Brief description of the drawings]
FIG. 1 is a side view of a cargo handling device with a fork moving device.
FIG. 2 is a front view of the same.
FIG. 3 is a plan view showing details of a load detection unit of the offset load detection device.
FIG. 4 is a sectional view taken along line AA of FIG. 3;
FIG. 5 is an exploded perspective view of a load detection unit.
FIG. 6 is a block diagram illustrating an electrical configuration of the unbalanced load detection device.
FIG. 7 is a side view showing a modified example of the load detector.
FIG. 8 is an explanatory diagram illustrating a container provided with four fork pockets in order to cope with a case where loads are unevenly loaded, and how to replace forks due to an uneven load.
[Explanation of symbols]
3, 4 ... fork bar 7 ... fork 10 ... load detecting unit 11 ... box 12 ... load sensor 13 ... roller 14 ... roller bracket

Claims (2)

Left and right forks are movably mounted along the upper and lower fork bars, and the forklift bias load detecting device includes a load detector for detecting a load applied between the left and right forks and the lower fork bar. And
The load detector includes a load sensor capable of detecting a load applied between the fork and the lower fork bar, and a pressing member that applies the load to the load sensor.
The load sensor is installed on the fork with a pressure receiving surface of the load sensor facing the lower fork bar,
The pressure member is provided movably in the front-rear direction with respect to the fork, and a roller bracket that abuts a pressure receiving surface of the load sensor, and is rotatably supported by the roller bracket and provided on a front surface of the lower fork bar. An unbalanced load detecting device for a forklift, comprising a roller that can roll . An unbalanced load detection device for a forklift according to claim 1,
On the fork, install a box that opens the rear surface,
The unbalanced load detecting device for a forklift , wherein the load sensor is fitted and accommodated in the box, and the roller bracket is further movably fitted in the front-rear direction .

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