JPS63180700A - Unmanned forklift - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application - This invention relates to a forklift that is equipped with a fork at the front that can be raised and lowered guided by a mast, and that runs unmanned on a predetermined track with a load placed on the fork. It is something.

1. Conventional technology - As an unmanned forklift truck developed earlier,
There is one disclosed in Japanese Patent No. 121251. This forklift is equipped with a detection device on the forklift or on its fingers that detects the shift of the load when the load interferes with, for example, the ceiling of a container or truck, or ground equipment during unmanned operation with a load on the front forks. It is equipped near the bar and has a function to stop traveling based on the detection.

□Problems to be solved by the invention□ Generally, when loading onto a container or truck, the cargo is often transported in a state where it is stacked in multiple tiers, such as two or three tiers, on forks. In that case, the top or both sides of the top of the topmost load is likely to interfere with the ceiling or side walls of the container or truck due to the load being tilted, the fork being lifted too much, or shaking vertically or horizontally. In the above-mentioned forklift, which is equipped with a load position detection device at a low position near the forks, if the lower load interferes with an obstacle, the shift of the load can be easily detected, but if the upper load is interfered with, the forklift can easily detect the shift of the load. When such occurrence occurs, it cannot be said that its detection will necessarily be carried out reliably and quickly. In particular, if the cargo in the upper tier is light and soft, interference in the upper tier is likely to be absorbed by deformation or damage to the cargo in the upper tier, or displacement of only the cargo in the upper tier, and therefore interference cannot be detected. It is possible that there may not be any, or there may be a considerable delay.

□Means for solving the problem□ The gist of this invention is that, as mentioned above, a fork that is guided by the mast and raised and lowered is provided in the front part, and a load is placed on the fork to move unmanned along a predetermined course. In a forklift that travels on a forklift, a load sensor that detects the displacement of the load on the fork is installed behind the load near the height corresponding to the upper end of the mast, and the forklift is operated based on the output of the load sensor. The point is that a stop command means for stopping is provided.

□Function and effect□ By doing this, when cargo is transported on the fork in multiple tiers, even if the upper tier of cargo interferes with the ceiling, side walls, etc. of the container or truck, the mast A load sensor installed at a height near the upper end of the forklift quickly detects a shift in the load, and the forklift is stopped based on this, so the load is more reliably protected. This will improve the trustworthiness of unmanned forklifts, and in turn lead to reductions in logistics costs by promoting the introduction of unmanned forklifts.

In addition, not only when transporting a relatively tall load, but also when transporting a relatively tall load, the displacement at the time of interference is usually larger at the top than at the bottom, so it is suitable for the upper part of the load. A load sensor located at a position that detects the displacement (shift) of the cargo at an early stage increases its sensitivity and reliability.

□Example□ Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIGS. 1 and 2, reference numeral 2 denotes a vehicle body, and the front wheels are drive wheels 4 and the rear wheels are steering wheels 6. The vehicle body 2 is provided with a balance weight 8 at the rear and a head guard 10 above. The head guard 10 is supported above the driver's seat 14 by two guide columns 12 erected on the left and right sides of the front of the vehicle body 2.

At the front of the vehicle body 2, as is well known, cargo handling devices including a fork 16, an outer mast 18, and an inner mast 20 are provided.

The inner mast 20 is guided in the vertical direction by the outer mast 18 via rollers, and the inner mast 20 further guides a lift bracket 22. A finger bar 26 is attached to the lift bracket 22 via a side shift attachment 24, and a pair of forks 16 are attached to the finger bar 26. Finger bar 26 is fixed to frame 28.

When the inner mast 20 is raised by the operation of the lift cylinder 30, the lift bracket 22 is moved by a chain (not shown). Finger bar 26 and fork 16 are raised together. The lower end of the outer mast 18 is connected to the vehicle body 2 so as to be rotatable around one axis.
8 and other cargo handling devices are tilted forward or backward.

Further, by the operation of the side shift cylinder 34, the finger bar 26 and the fork 16 are moved to the lift bracket 2.
2, the vehicle body 2 is side-shifted in the left-right direction.

Two lateral displacement sensors 40 are attached to the sides of the vehicle body 2 to unmannedly guide the forklift 38 along the guide wall 36. These lateral displacement sensors 40 are connected to the vehicle body 2.
It is provided with an in/out member 44 that can be moved in and out from a box 42 fixed to the box 42, and this in/out member 44 is brought into contact with the guide wall 36 via a roller 46, so that the amount of in/out of the in/out member 44 is detected by, for example, a linear potentiometer. It has become. The distance between the vehicle body 2 and the guide wall 36 and the inclination (driving posture) of the vehicle body 2 about the vertical line with respect to the guide wall 36 are detected by the output signals of both of these lateral displacement sensors 40.

The frame 28 to which the finger bar 26 is fixed is provided with lower load sensors 48, one on each side. This lower load sensor 48 is of a contact type, for example, and is located at a position corresponding to the back surface of the lower part of the load W.
A built-in proximity switch or the like is used to detect the shift of the cargo W on the top.

On the other hand, one upper load sensor 50 is provided corresponding to the upper part of the load W at a predetermined distance in the left-right direction of the vehicle body 2. The upper load sensor 50 is fixed to the tip of each stay 52 that extends forward from each of the guard columns 12 that support the head guard 10. Upper load sensor 50
The height position of is set to be slightly lower than the upper end of the outer mast 18 (approximately corresponding to the upper end of the inner mast 20 at the lowering end position), so that it corresponds to the back of the upper end of the cargo W, and the height position of the cargo W is If the sensor is a contact type that detects the displacement of the upper part, the displacement of the upper part pushes the detector and activates a built-in proximity switch or the like.

FIG. 3 shows a control circuit for this unmanned forklift 38. The lateral displacement sensor 40. The lower load sensor 48 and the upper load sensor 50 are connected to the I10 interface 60 of this control circuit, and the I10 interface 60
constitutes a microcomputer together with the CPU 62 and memory 64. The I10 interface 60 further includes a travel control circuit 66, a steering control circuit 68.
A brake control circuit 70 and a cargo handling control circuit 72 are connected, a drive motor 74 that drives the drive wheels 4 is connected to the travel control circuit 66, and a steering control circuit 6
8 is a steering motor 76 that steers the steering wheel 6;
is connected. The brake control circuit 70 also includes an electromagnetic brake 7 that brakes the motor shaft of the drive motor 74.
8 is connected, and an electromagnetic pulp 82 that controls oil pressure to a hydraulic brake 80 that brakes each drive wheel 4 is also connected. Furthermore, the cargo handling control circuit 72 includes the lift cylinder 30. Tilt cylinder 32. An electromagnetic pulp 84 that controls the supply of hydraulic pressure to the side shift cylinder 34 is connected, and the operation of the cargo handling device 86 including the fork 16 and the lift bracket 22 is controlled by this control.

As shown in FIG. 1, for example, the unmanned forklift 38 as described above loads the cargo W in three stacks on the fork 16 in a state that it can move a short distance backwards, and travels unmanned to a container, truck, or the like. Based on a signal from a lateral displacement sensor 40 in contact with the guide wall 36, the steering motor 76 is controlled so that the distance between the vehicle body 2 and the guide wall 36 is maintained within a predetermined range.

During unmanned driving, if the lower part of the load W (lower or middle load) interferes with the container, side wall of the truck, or ground equipment, the lower load sensor 48 quickly detects the deviation and sends an output signal to the CPU 62. As a result of the supply, the drive motor 74 is stopped via the travel control circuit 66, and
The electromagnetic brake 78 and the hydraulic brake 80 are operated via the brake control circuit 70, and the forklift 38 comes to an emergency stop.

In addition, when the upper part of the load W (upper load) interferes with the side wall or ceiling of the container or truck, the upper load sensor 50 sensitively detects the displacement. As shown in FIG. 5, in a situation where the upper cargo W interferes with the rear ceiling edge or side wall edge of the container 88 due to the horizontal inclination, only the upper cargo W tends to shift backward. The upper load sensor 50 provided corresponding to the height position quickly detects the displacement of the load W on the upper stage and issues an output signal.

As a result, the above-mentioned stop command means, that is, the CPU
The unmanned forklift 38 comes to an emergency stop in response to a stop command from the microcomputer 62, the travel control circuit 66, and the brake control circuit 70.

Note that the tilt control of the forklift 38 is performed by the fork 16.
Alternatively, when the detection is performed by detecting the angle of the cargo W, as in the above embodiment, the guard support column 12 of the head guard 10, etc.
It is effective to attach the upper load sensor 50 to the forklift body, which has a small angle change with respect to the ground side, via the stay 52 or the like in order to improve detection accuracy.

In addition, when tilt control is performed to keep the angle of the mast 18 of the forklift 38 constant, the upper load sensor 50 is attached to the mast 18 via a stay or the like, so that the deflection of the fork 16 due to the difference in weight of the load W is controlled. It is also possible to detect interference outside the range in which the distance between the load W and the upper load sensor 50 changes.

Further, in the above embodiment, by using the lower load sensor 48 and the upper load sensor 50 in combination, it is possible to quickly and reliably detect the interference of the load W, regardless of whether the interference location is on the lower side or the upper side. , can be said to be a desirable aspect for protecting the cargo W. However, when the load is not stacked on the fork 16 in multiple stages, but rather a relatively tall load is generally transported, the displacement (shift) when the load interferes is usually large at the top. Therefore, interference can be sufficiently detected even if the lower load sensor 48 is omitted and only the upper load sensor 50 is used.

Further, the upper load sensor 50 and the like can be replaced with other sensors including an optical sensor. Furthermore, the upper load sensor 50 or the lower load sensor 48 is capable of detecting displacement in two stages, detecting completion of the fork insertion at the first position of the load and stopping the insertion; It can also be configured to detect interference between cargoes at two positions and make an emergency stop.

Although not described in detail, it goes without saying that the present invention can be practiced with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a side view schematically showing an unmanned forklift truck according to an embodiment of the present invention, and FIG. 2 is a plan view thereof. FIG. 3 is a block diagram showing the control circuit of the forklift. FIG. 4 is a diagram showing an example of cargo interference,
FIG. 5 is a diagram of the interference location seen from the rear. 10: Head guard

Claims (1)

[Claims] In a forklift that is equipped with a fork at the front that can be raised and lowered guided by a mast, and that runs unmanned along a predetermined track with a load placed on the fork, a vehicle is placed behind the load near the height position corresponding to the upper end of the mast. An unmanned forklift comprising: a load sensor for detecting the displacement of the load on the fork; and stop command means for stopping the forklift based on the output of the load sensor.