JPH031239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cargo handling device for a forklift, and more particularly to an automatic cargo handling device for loading and unloading cargo using the forks of a forklift.

In recent years, when carrying out loading operations using forklifts, the lifting height has increased, and loading and unloading is sometimes performed at a height of 10 meters or more. At that time, it becomes difficult for the driver to adjust the height to the desired height while looking at the tip of the claw, which is more than 10 meters above the driver's seat. Therefore, it is desirable to be able to easily unload and load cargo at a predetermined height position by the driver.

However, conventionally, a limit switch is provided on the mast or the fork claw in order to stop the fork claw at a certain predetermined position, and when the claw reaches that position, for example, 8.5 m, a lamp is turned on in the operation control section. Or, the drive source for lifting the load would be turned off. However, since the desired height position is determined by which shelf on the shelf the items are to be loaded and unloaded, it is necessary to provide the required number of limit switches, for example 10, corresponding to the desired height position. Also, if the work location changes and you want to load and unload items on another shelf, but the height of the shelf is different from the previous one, a more complicated control device is required, making the work practically impossible. Ta.

The present invention has been made in view of the above-mentioned points, and its purpose is to detect the movement of the chain that changes depending on the load lifting process, as well as to detect the presence or absence of a load at the fork claw part, and to transmit these detection signals to the load lifting process. A highly reliable automatic cargo handling system for forklifts that can be used effectively as a control signal for the operation unit and automatically perform loading and unloading operations by correcting the fork so that it stops at a predetermined height above the cargo height. The goal is to provide the following.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An automatic cargo handling device according to an embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a forklift truck to which the present invention is applied, and numeral 1 designates a mast portion pivotably mounted on the front portion of the vehicle body. The mast section 1 is composed of an outer mast 1a and a column 1b slidably provided on the outer mast 1a, and a fork 2 is attached to the lower part of the column 1b.
Further, a lifting drive section is provided at the front of the vehicle body, and this lifting drive section is operated by a hydraulic cylinder 3a vertically fixed to the front surface of the vehicle body and a piston 3b housed within this cylinder 3a. It is configured. A chain wheel support 4 is fixed to the upper end of the piston 3b, and chain wheels 5 are provided on both sides of the chain wheel support 4. 6 has one end with fork 2 as support 1b
The lift chain is connected to a bracket 7 for connection to the cylinder 3a, and the other end is connected to the cylinder 3a.

Therefore, when the operating lever 8 is operated, oil is force-fed into the cylinder 3a by the hydraulic system, and the fork 2 is raised. The height of the fork claw 2 of this fork 2 is sometimes more than 10 m from the floor surface. The chain wheel 5 moves up and down due to the up and down movement of the piston 3b. In this case chain 6
is fixed on one side, so chain wheel 5 rotates, which causes wheel 5 of chain 6 to rotate.
The engaging part of the chain 6 changes and it appears that the chain 6
will be transferred.

The present invention detects the moving state of the chain 6 or the rotating state of the wheel 5, and controls the moving state of the fork 2 by effectively utilizing this detection signal. That is, as shown in FIGS. 3 and 4, a detector 10 is provided oppositely to the part of the chain wheel 5 where the chain 6 engages with a predetermined distance therebetween, and this detector 10 is attached to the mounting piece 8. Therefore, it is fixedly attached to the chain wheel support 4. As shown in FIG. 5, the chain 6 has a cylindrical roller 11 rotatably inserted into a connecting pin 9. Therefore, as the detector 10, an electromagnetic pulse pickup 10a is used.

6 and 7 show the drive control section of the load lifting device according to the present invention, and in FIG.
1 is a battery which is a DC power source, and 13 is a cargo handling motor, which has an armature 13a and a series field winding 13b. 15 is the first main relay, 16 is the second main relay, 17 is the first auxiliary relay, and 18 is the second
This is an auxiliary relay. The cargo handling motor 13 is connected to the battery 12 via a normally open contact 15a of a first main relay 15 and a current adjustment resistor 14 for adjusting the current of the cargo handling motor 13. Normally closed contacts 16a of the main relay 16 are connected in parallel. Therefore, the contact 15a,
A cargo handling drive circuit A is constituted by the drive motor 13, the resistor 14, and the contact 16a.

In addition, as shown in FIG. 6, the first main relay 15
is connected in parallel to the cargo handling drive circuit A via the cargo handling operation switch 19 and the normally closed contact 17a of the first auxiliary relay 17, thereby forming a starting circuit B. The second main relay 16 is connected to the battery 12 via a normally closed contact 18a of a second auxiliary relay 18.
A speed adjustment circuit C is configured. 1st
The auxiliary relay 17 is the first switching element 20
The second auxiliary relay 18 is connected to the battery 12 via a to form a stop command circuit D, and the second auxiliary relay 18 is connected to the battery 12 via a second switching element 20b to form a deceleration command circuit E. Ru. Further, the stop command circuit D and the deceleration command circuit E receive a deceleration command from the command circuit F shown in FIG.
S ₁ and stop command S ₂ are supplied.

As the command circuit F, a microcomputer 21 is used as shown in FIG. 7, and the computer 21 mainly has an input/output section 22, a central processing section 23, and a memory 24 as a storage section. Further, in FIG. 7, 25 is a dead zone designation switch, 26 is a storage command switch, 27 is an automatic operation switch, and 28 is a stage number designation switch having stage number position designation contacts 28a to 28n. Further, the microcomputer 21 receives a load detection signal _S3 from the load detection section G, which detects whether a load is placed on the claw portion 2a of the fork 2.

The load detection part G detects the load 41 on the fork claw part 2a.
A contact 32 that turns on when the is loaded and this contact 32
A DC power supply, for example, a small-capacity battery 34, is connected through a resistor 33. A positive electrode of a battery 34 is connected to the contact 32 via a resistor 33, and a negative electrode of the battery 34 is connected to the earth 35. The 10th contact point 32
As shown in the figure, a normally open contact of a micro switch 36 disposed on the claw portion 2a of the fork 2 is used.
That is, a long groove 37 is provided on the upper surface of the claw portion 2a of the fork 2 along the axial direction thereof, and a micro switch 36 is disposed in this long groove 37. Further, a base portion of a lever 38 is rotatably connected to the claw portion 2a, and a spring 39 is elastically loaded at the tip portion of the lever 38 so as to be positioned within the long groove 37. Therefore, when a load is placed on the claw portion 2a of the fork 2, the lever 38 rotates against the spring force of the spring 39, and the contact 32 of the micro switch 36 is turned on.

Next, the operation of the loading device having the above configuration will be explained.

When the operation lever 8 shown in FIG. 2 is operated, the load operation switch 19 in the load operation circuit shown in FIG.
a is thrown in. As a result, the load motor 13 is started by the current supplied through the contacts 15a and 16a. This causes the hydraulic system to operate, forcing oil into the cylinder and causing the fork 2 to rise. At this time, as shown in FIGS. 3 and 4, each time the roller 11 of the chain 6 passes near the electromagnetic pulse pickup 10a, a pulse train as shown in FIG. 8 is obtained. This pulse train is input to the microcomputer 21 of the command circuit F as shown in FIG. It will correspond to whether it has risen.

Now, as shown in Figure 2, the claw part 2 of the fork 2
Assuming that a is on the floor and the operating lever 8 is operated to the load lifting side, the claw portion 2a rises from the floor. For example, when the pulse from the pulse pick-up 10a is the 100th, the claw part 2 of the fork 2 is at a height of about ₃ m from the ground, so if you want to stop the fork 2 at a position of 6 m, All you have to do is issue a stop command at the 200th pulse. However, if, for example, a valve (not shown) in the hydraulic system is closed at exactly the 200th pulse, the fork 2 will come to a sudden stop, and there is a risk that the load will be dislodged by the shock. Therefore, when stopping at the scheduled 200th pulse, the deceleration command S ₁ is issued when there is, for example, 180 pulses before that. Its deceleration command S ₁
Therefore, a series resistance 1 is applied to the hydraulic motor 13 shown in FIG.
4 to lower the motor speed, that is, the load lifting speed.

More specifically, the deceleration command circuit F shown in FIG.
For example, when the claw part 2a of the fork 2 is at the bottom as shown in Fig. 2, the height l _{1 is} 50 cm from the floor.
It is arranged so that the pulses from the pulse pickup 10a are not counted when the pulse pickup 10a is present. When a normal forklift is operated, the claw portion 2a of the fork 2 is moved at a position of 20 to 30 cm above the floor.
Then, the user runs to the front of the shelf 29 and operates the load lever 8 to unload the load to a predetermined height or load the load there. At this time, at a predetermined height, the fork 2
The number of pulses from the pulse pickup 10a is counted to stop the claw portion 2a. In this method, the stopping position will shift by 10 cm depending on whether the height of the claw portion 2a before loading is 20 cm or 30 cm. It would be possible for the driver to lower the claw portion 2a to the floor before lifting the load and then start lifting the load, but this is cumbersome. Therefore, in the present invention, a detector is provided to detect when the claw part 2a passes a position _l1 , that is, about 50 cm from the floor surface and rises, and at that point, an enable signal is outputted to start effective counting. There is. The detector has a limit switch 25 attached to the mast 1 that is turned on when the claw portion 2a rises by about 50 cm. By providing this limit switch 25, the driver can move the fork 2 in front of the shelf 29.
There is no need to restart after dropping the fork claw part 2a, and the stopping position is constant by stopping the fork claw part 2a at a certain number of meters from the reference point.

The position of the electromagnetic pulse pickup 10a is preferably near the top of the chain support wheel 5, as shown in FIGS. 3 and 4. This is because the roller 11 of the chain 6 and the electromagnetic pulse pickup 10a are far apart in this area, and the roller 11,
This is because the gap D between the adjacent rollers is almost eliminated in the flat portion of the chain 6.

To describe the operation in detail, when lifting a load, as shown in FIG. 2, the fork claw portion 2a is placed at an arbitrary position 50 cm or less ( ₁₁ or less) above the floor and the following operating procedure is carried out.

(1) First, the driver turns on the storage command switch 26 in the command circuit section F shown in FIG.

(2) Turn on the switch 28a for specifying the number of stages to be stored, for example, "4th stage".

(3) Operate the loading lever 8 and visually stop the fork claw portion 2a at the fourth stage position of the shelf 29, for example, 6 m from the floor.

(4) Turn off the storage command switch 26, and then turn off the stage number designation switch 28.

(5) Next, if you want to memorize the 6th row, for example, return the fork claw part 2a to near the floor level.

(6) Turn on the memory switch 26.

(7) Turn on the "6th stage" stage number switch 28f.

(8) Operate the loading lever 8 to release the fork claw part 2a.
Raise it to the 6th step.

(9) Thereafter, the same operation is repeated to store an arbitrary number of stages in the microcomputer 21.

After that, the actual operation started and a certain baggage was placed on the 6th shelf of shelf 29.
If you want to put it on the tier, run to the front of the shelf 29 and (10) turn on the tier switch for "6th tier".

(11) Operate the loading lever 8 while turning on the automatic operation switch 27. In this case, it is preferable that the automatic operation switch 27 be interlocked with the loading lever 8.

(12) Fork claw part 2a rises to about 50cm above the floor.
The microcomputer 21 starts counting the number of pulses, decelerates just before the sixth stage, and eventually stops at the previously memorized position of the sixth stage.

That is, in the load handling circuit shown in FIGS. 6 and 7, the chain position detector 10, that is, the electromagnetic pulse pickup 10 outputs a pulse signal 30 as the chain 6 moves, as shown in FIG. Output. This pulse signal is input to the microcomputer 21 of the command section F. In the computer 21, an input/output section 22, a central processing section 23, and a memory 24 count the pulse signals 30 and perform arithmetic processing and storage operations.

When the fork claw portion 2a rises by a predetermined height _l1 , the limit switch 25 is turned on, and the microcomputer 21 performs effective counting of the pulse signals 30. At this time, curve 31 in FIG.
As shown in the straight line portion 31a, the loading speed V is at a constant value. The computer 21 has a pulse number N
When the valid count reaches 1 to (n-p) pulses, a deceleration command signal _S1 is issued. This deceleration command signal _S1 is supplied to the base of transistor 20l in FIG. 6, thereby turning on transistor 20.

When transistor 20 is turned on, second auxiliary relay 18 is energized, its contact 18a is turned off, and second main relay 16 is deenergized. When the main relay 16 is deenergized, the contact 16a is turned off and the motor current is limited. As a result, as shown by the curve 31b in FIG. 9, the loading speed V gradually decreases and the speed V decreases.

Next, the computer counts a predetermined n-th pulse, issues a stop command signal _S2 , and supplies it to the base of the transistor 20a. As a result, the transistor 20
a is turned on, and the first auxiliary relay 17 is energized. When the auxiliary relay 17 is energized, the contact 17a is turned off and the first main relay 15 is deenergized. As a result, the contact 15a in the drive circuit A is turned off, the rotation of the load motor 13 is stopped, and the fork pawl portion is gently stopped at a predetermined position.

As is clear from the above description, the automatic load lifting device of this embodiment provides the following various advantages.

(a) Once the arbitrary height of the fork claw portion 2a is memorized in the microcomputer 21, which is the arithmetic processing section, the position designation switch 28 can be used from the next time.
When the driver inserts the load and lifts the load, the fork claw portion 2a automatically stops at that position, making the operation easier for the driver.

(b) Memory can be cleared and re-memorized appropriately, so even if the working location of the forklift changes or the height of the shelf changes, once the memory operation is performed, the fork will be automatically moved to the appropriate position next time. It can be stopped.

(c) It is not necessary to provide many limit switches as in the past, and if the storage capacity of the arithmetic processing unit is increased,
It can also remember all the locations the forklift works.

(d) Since a reference point signal (microcomputer ENABLE signal) is provided, when automatically lifting a load, there is no need to lower the fork claw part 2a to the floor and then lift the load again.

(e) Since the electromagnetic pulse pickup 10a is disposed on the top of the chain support roller 5, the movement of the chain 6 can be detected reliably.

(f) Since the deceleration command is automatically calculated from inside the microcomputer and the machine is operated at low speed before stopping, the stopping position accuracy is good and there is no need to worry about the load shifting when stopping.

Further, in the command circuit F, as shown in FIG. 7, a correction signal _S3 is inputted from the load detection section G, and the arithmetic processing section performs arithmetic processing to obtain an appropriate stop command signal _S2.
This is what you get. That is, it is detected whether a load is placed on the fork 2, and if it is, it is regarded as unloading work and the automatic load stop position is moved up by a predetermined distance l.

Assume that the fork claw portion 2a is stored and set at, for example, the height l of the "sixth step" as shown in FIG. 11 without any load. When unloading work is performed by automatic operation after that, the pallet 41 at the height l set in memory.
Since the height Δl is insufficient, unloading onto the shelf 29 becomes impossible.

Therefore, in this embodiment, if the pallet 40 is present in the fork claw section 2a, the load detection section G shown in FIG.
The contact 32 turns on, and the resistor 34 is transferred from the battery 34.
A correction signal _S3 of, for example, 5V is input to the microcomputer 21 through the microcomputer 21. The computer 21 processes the correction signal _S3 and the pulse signal from the detector 10, and issues a deceleration command signal _S1 at the 180th pulse.
Instead of issuing the stop command signal _S2 at the 183rd pulse, the deceleration command _S1 is issued at the 183rd pulse, and the stop command signal _S2 is issued at the 203rd pulse. Make it stop at the height. After the fork 2 stops at the height (l + Δl), by adjusting the forklift by moving it back and forth a little, the cargo 41 can be unloaded onto the shelf 29 via the pallet 40 as shown in FIG. . Furthermore, the pallet 4 is attached to the fork claw part 2a.
1 is placed so that the height is (l + Δl), or when a normally closed contact is used as the contact 32, the computer 21 has the above-mentioned settings. may be performed by performing the opposite calculation process.

As explained above, the present invention detects the movement of the chain or wheel related to the ascent of the fork to obtain a pulse signal, and after arithmetic processing of the number of pulse signals together with the number of pulses stored in advance by the arithmetic processing section, the fork Since the movement state of the fork is controlled by giving a deceleration command and a stop command to the drive unit, the forklift can automatically load and unload cargo with high precision.

Furthermore, in the present invention, it is detected whether or not there is a pallet on the fork, and if there is, it is considered as unloading work and the automatic loading stop position is set slightly higher, so unloading work can be carried out without any problem. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is a front view of a forklift to which the present invention is applied, FIG. 2 is a side view thereof, and FIG. 3 is a front view showing a part of an automatic cargo handling device according to an embodiment of the present invention.
Figure 4 is its side view, Figure 5 is its partially enlarged view,
Figures 6 and 7 are electrical circuit diagrams of the drive control section, and Figure 8
The figure is a pulse waveform diagram, Figure 9 is a characteristic diagram of the automatic cargo handling device, and Figure 10 is an enlarged side view of the main parts of the automatic cargo handling device.
FIG. 11 and FIG. 12 are explanatory diagrams of the operation of the automatic cargo handling device of the present invention. 1...Mast part, 1a...Outer mast, 2...
...Fork, 2a...Fork claw part, 3a...
Cylinder, 3b... Piston, 5... Chain wheel, 6... Chain, 10... Detection section, 11
... Chain roller, 21 ... Arithmetic processing section, 25
...Limit switch which is a dead zone designation switch, 32...Contact point, 36...Micro switch,
37... Long groove, 38... Lever, 39... Spring,
40...pallet, 41...baggage, F...command circuit, G...load detection unit.

Claims (1)

[Claims] 1. A mast section vertically installed on a forklift vehicle body, a fork movably provided on the mast section, a drive section that drives the fork up and down via a string and a wheel, and a drive section that lifts and lowers the fork via a string and wheels. A cargo handling device comprising: a drive control section for controlling operation; a correction means for correcting the movement distance of the fork by the height of the pallet based on a load detection signal from the load detection means; and a correction means for storing a preset movement distance of the fork and using the detection signal from the detection section and the correction means. an arithmetic processing unit that issues a deceleration command for the drive unit and issues a stop command for the drive unit after a predetermined time by processing a correction signal obtained by a command circuit including dead zone designation means for stopping the calculation of the section;
A deceleration means for decelerating the drive speed of the drive unit in response to a deceleration command from the command circuit, and a stop means for stopping the drive unit in response to the stop command after the drive unit has been decelerated by the deceleration means. An automatic cargo handling device for a forklift that is characterized by: