JPS6223720B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a loading device for a forklift, and more particularly to an automatic loading device for a forklift.

In recent years, the height of loading using forklifts 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 automatically detect the movement of the chain that changes depending on the load lifting process, and to effectively use this detection signal as a control signal for the load operation section. To provide an automatic loading device for a forklift that is capable of loading a load and is highly reliable by controlling a reference value for switching to automatic operation when the fork reaches a predetermined height. .

DESCRIPTION OF THE PREFERRED EMBODIMENTS An automatic loading 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 2a 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 this chain 6,
This detection signal is effectively used to control the movement state of the fork 2. That is, as shown in FIG. 3, a detector 10 is installed at a portion of the chain wheel 5 where the chain 6 is connected with a predetermined distance apart, and this detector 10 is attached to the chain wheel by a mounting piece 8. Fixed to support 4. As the detector 10, an electromagnetic pulse pickup 10a is used.

4 and 5 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 load motor, which has an armature 13a and a series field winding 13b. 15 is a first main relay, 16 is a second main relay, 17 is a first auxiliary relay, and 18 is a second auxiliary relay. The load 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 load motor 13.
A normally closed contact 16a of the second main relay 16 is connected in parallel to 4. Therefore, the load drive circuit A is constituted by the contact 15a, the drive motor 13, the resistor 14, and the contact 16a.

In addition, as shown in FIG. 4, the first main relay 15
is connected in parallel to the load drive circuit A via the load 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. 5, 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. 5, 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. When the operating lever 8 shown in FIG. 2 is operated, the load operation switch 19 in the load operation circuit shown in FIG. 6 is turned on, the first main relay 15 is energized, and the contact 15a is closed. 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. 6 is obtained. This pulse train is input to the microcomputer 21 of the command circuit F as shown in FIG.
By counting this number of pulses, it corresponds to how many meters the chain 6 has moved, that is, how many meters the chain support wheel 5, that is, the fork 2 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 100th pulse is received from the pulse pick-up 10a, the claw part 2 of the fork 2 will be at a height of about ₃ m from the ground, so I would like to stop the fork 2 at a position of 6 m. Sometimes it is sufficient to 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. The deceleration command
By _S1 , a series resistor 14 is inserted into the hydraulic motor 13 shown in FIG. 4 to reduce the motor speed, that is, the load lifting speed.

More specifically, in the deceleration command circuit F shown in FIG. 5, when the claw portion 2a of the fork 2 is in the lower position as shown in FIG. A dead zone is set to prevent counting. 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, to stop the claw part 2a of the fork 2 at a predetermined height,
The number of pulses from the pulse pickup 10a is counted. 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 complicated. Therefore, in the present invention, as shown in Fig. 8, a reference point detector is provided to detect when the claw part 2a passes a position _I4 , that is, about 50 cm from the floor surface and rises, and starts effective counting at that point. An enable signal is provided to enable the operation. The reference point detector is attached to the mast 1 and is activated when the claw portion 2a rises by about 50 cm, and its normally closed contact 25a is turned on. By providing a reference point detector, the driver does not have to lower the fork 2 in front of the shelf 29 and then restart it, and the fork claw 2a can also be stopped at a certain number of meters from the reference point to determine the stopping position. is constant.

More specifically, when lifting a load, as shown in FIG. 2, the fork claw portion 2a is placed at an arbitrary position 50 cm or less above the floor ( _I3 or less) and the following operating procedure is performed.

(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 operating 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 surface.

(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 operating 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 control 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 operating lever 8.

(12) The fork claw part 2a rises, the microcomputer 21 starts counting the number of pulses at about 50 cm above the floor, 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. 4 and 5, the chain position detector 10, that is, the electromagnetic pulse pickup 10a 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 _I4 , the enable switch 25a is turned on, and the microcomputer 21 performs effective counting of the pulse signals 30. At this time, as shown by the straight portion 31a of the curve 31 in FIG. 7, the lifting speed V is at a constant value. The computer 21 issues a deceleration command signal _S1 when the effective count of the number N of pulses is 1 to (np) pulses. This deceleration command signal _S1 is supplied to the base of transistor 20b in FIG. 4, thereby turning on transistor 20b.

When transistor 20b is turned on, second auxiliary relay 18 is energized, its contact 18a is turned off, and second main relay 16 is deenergized. Main relay 16
When the contact 16a is deenergized, the contact 16a is turned off and the motor current is limited. As a result, curve 31b in FIG.
As shown, 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 claw portion 2a of the fork 2 is gently stopped at a predetermined position.

However, when memory operations are performed without load,
For example, fork 2 is operated under load during actual work.
Suppose that when a ton of load is applied, the front wheels of a forklift sag due to the load, for example, by 5 cm. In this case, when there is no load, the claw part 2
When a became 50 cm, the reference point signal was being output, but due to the deflection of the front wheel, the reference point signal will be output when the claw portion 2a is at a position of 45 cm. As a result, the stopping position during automatic operation, which was originally scheduled to be 6.0 m, becomes 5.95 m, causing an inconvenience. Therefore, in the present invention, a dead zone adjustment section is provided in the forklift as shown in FIGS. 8 to 10.

That is, FIG. 8 shows a first example of the dead zone adjustment section used in the automatic load loading device of the present invention, in which a hollow cylindrical bearing frame 32 is fixed to the outer lower end of the outer mast 1a. This bearing frame 3
2 is provided with a positioning rod 33 slidably inserted therein for determining the dead zone _I1 . Bearing frame 32
A spring receiver 34a is provided at the upper end, and a spring receiver 34b is fixed to the positioning rod 33 so as to be located at the lower part of the bearing frame 32.
A spring 35 is loaded between 4a and 34b.
An auxiliary wheel 36 is attached to the lower end of the positioning rod 33, and the upper end of the auxiliary wheel 36 engages with a fork support frame 37 attached to the outer mast 1a.
The distance to the actuating piece 38a of the limit switch 38 is set to _I4 , the effective detection distance of the limit switch 38 is _I0 , and the distance from the engaged part, that is, the lower end of the fork support frame 37 to the floor surface is set to ΔI. I ₄ = (I ₀ + Δ
become I). ΔI changes almost in inverse proportion to the load on the fork 2, and as ΔI increases, I ₀ decreases, and as ΔI decreases, I ₀ increases.

When the fork 2 rises from the position of the claw portion 2a of the fork 2 shown in FIG. 8, a pulse signal 30 is supplied from the chain position detector 10 to the command circuit F shown in FIG. Claw part 2a of fork 2
increases by _I0 , a number of pulses 30 proportional to this _I0 are supplied to the command circuit F, and at this time, the actuating piece 38a of the limit switch 38 disengages from the fork support frame 37, as shown in FIG. switch 25
a turns on. When the switch 25a is turned on, an enable signal is supplied to the microcomputer 21 of the command circuit F, which causes the computer 21 to process the pulse signal from the chain position detector 10 as shown in FIGS. 6 and 7. When the computer 21 counts the number of pulses (n-p), it issues a deceleration command _S1 , and thereafter, when it counts the number of pulses n, it issues a stop command _S2 .

Therefore, if the setting is such that a reference point signal is generated when the height of the claw section 2a exceeds a position of 50 cm above the floor, if the front wheel of the forklift sinks by 5 cm due to the load on the fork claw section, I ₀ will be It grows by 5cm. Therefore, when there is no load, for example, the deceleration command S ₁ is issued at the 180th pulse, and the stop command signal S ₂ is issued at the 200th pulse.
The fork claw portion 2a is stopped at a predetermined height by emitting a deceleration command signal _S1 at the 202nd pulse and a stop command signal _S2 at the 202nd pulse. Note that when the storage operation is performed with a load applied to the fork 2, the arithmetic processing unit may be caused to perform the calculation opposite to the above.

Figure 9 shows another example of the dead zone adjustment section.
Magnetic proximity switch 39 instead of limit switch
A permanent magnet 40 is disposed at the lower end of the fork support frame 37 as an operating piece. When the fork 2 rises and the permanent magnet 40 comes to the position of the proximity switch 39, the proximity switch 39
The contact 25a is closed and an automatic operation command is issued. In this case, the computer 21 may be programmed to start counting the pulse signals from the chain position detector 10 in response to an instantaneous ON signal of the enable contact 25a in the command circuit F shown in FIG.

FIG. 10 shows still another example of the dead zone adjustment section, in which a magnetic proximity switch 39 is attached to the upper end of the positioning rod 33, and an operating piece is attached to the opposing surface of the fork support frame 37. A strip-shaped permanent magnet 41 is attached.

In the dead zone adjustment section shown in FIG. 10, when the claw portion 2a of the fork 2 is at the lowest position, the proximity switch 39 is on. Operate the operating lever 8 to raise the fork 2 and give an actual driving command to the command circuit F. After a predetermined time e.g. 0.2 seconds after the fork 2 starts to rise, the claw part 2a
passes the position of proximity switch 39, which turns off. In this case, in the command circuit F of FIG. 5, the effective on time of the enable switch 25a is 0.2 seconds. Therefore, if the computer 21 is programmed to operate when the enable switch 25a remains on for 0.2 seconds, the same actions and effects as in the above-mentioned examples can be obtained.

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

(a) Once the arbitrary height of the fork claw portion 2a is stored in the microcomputer 21, which is the arithmetic processing unit, the position designation switch 28 can be used from the next time.
When the fork claw section 2a is loaded and loaded, 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) Reference point signal (microcontroller ENABLE signal)
Since this 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 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.

(f) Furthermore, in this embodiment, the error signal of the dead zone distance caused by the weight of the cargo loaded on the fork 2 is corrected. Therefore,
The most important advantages obtained by this embodiment are:
A reference point signal can always be obtained regardless of the load on the fork 2, and precise automatic driving operation becomes possible.

As explained above, the present invention detects the motion of a chain or wheel related to the movement of a fork to obtain a pulse signal, and after processing the number of pulse signals together with a pre-stored number of pulses in an arithmetic processing section, the fork moves. The moving state of the fork is controlled by giving a command to decelerate the drive unit and also a command to stop. Therefore, according to the present invention, since the reference value for switching to automatic operation when the fork reaches a predetermined height is controlled at a constant level, cargo can be loaded and unloaded onto the forklift automatically and with high precision. The effect is great.

[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 loading device according to an embodiment of the present invention.
Figures 4 and 5 are electrical circuit diagrams of the drive control section;
FIG. 7 is a pulse waveform diagram, FIG. 7 is a characteristic diagram of the automatic load loading device, and FIGS. 8 to 10 are schematic configuration diagrams showing modified examples of the dead zone adjustment section. 1...Mast part, 1a...Outer mast, 2...
...Fork, 2a...Fork claw part, 3a...
Cylinder, 3b... Piston, 5... Chain wheel, 6... Chain, 10... Detection unit, 11
... Chain roller, 21 ... Arithmetic processing section, 25
a... Enable switch, 32... Bearing frame, 3
3... Positioning rod, 35... Spring, 36... Auxiliary wheel, 37... Fork support frame, 38... Micro switch, 39... Proximity switch, 40, 41
...Permanent magnet, F...Command circuit.

Claims (1)

[Claims] 1. A mast section that is rotatably installed vertically on a forklift vehicle body, a fork that is movably provided on the mast section, a drive section that drives the fork up and down via a string and a wheel, and the drive section. a fork movement detection section that detects a movement state of the cord relative to the wheel according to movement of the fork; a support member fixed to the mast section; , a positioning rod loosely inserted into the support member; a biasing portion for applying a force in a direction that brings the positioning rod into constant contact with the floor surface; and a biasing portion disposed between the positioning rod and the fork, the fork a switch section that generates an enable signal on the condition that the fork has moved upward a predetermined distance from the floor surface to the mast section; and a preset moving distance of the fork is stored based on the enable signal from the switch section. a command circuit including a calculation processing unit that processes a detection signal corresponding to the movement of the string from the fork movement detection unit to issue a deceleration command for the drive unit and also issues a stop command for the drive unit after a predetermined time; An automatic loading device for a forklift, characterized by comprising: