JPS6215480B2 - - 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, 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 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. An object of the present invention is to provide a highly reliable automatic loading device for a forklift, which allows loading operations to be carried out in a timely manner.

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 loading 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 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 load 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 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. The normally closed contacts 16a of the two main relays 16 are connected in parallel. Therefore, the contact 15a,
A load 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 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 connected to the first switching element 2
A stop command circuit D is connected to the battery 12 via 0a, and a second auxiliary relay 18
is connected to the battery 12 via the second switching element 20b, and constitutes a deceleration command circuit E. Further, the stop command circuit D and the deceleration command circuit E are supplied with a deceleration command S ₁ and a stop command S ₂ from the command circuit F shown in FIG.

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.

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

When the load 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 transmitted to the microcomputer 2 of the command circuit F as shown in FIG.
1, and by counting the 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 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 complicated. 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 an effective count. 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 the fork claw part 2a after the reference point, and the stopping position is fixed 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 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 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) 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. 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 dead zone designation switch 25 is turned on, and the microcomputer 21 performs effective counting of the pulse signals 30. At this time, curve 3 in Figure 9
As shown in the straight line portion 31a of No. 1, the loading 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 (n-p) pulses. This deceleration command signal _S1 is supplied to the base of transistor 20b in FIG. 6, 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 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.

10 and 11 show a modification of the fork movement detecting section, that is, the chain movement detecting section 10. In FIG. That is, as shown in FIGS. 10 and 11, a pulse generating gear 42 is attached to the shaft 5a of the chain support roller 5, which is a chain wheel, concentrically with the support roller 5 and on the outside. Opposing the tooth portion 42a of 42,
As shown in FIG. 11, a photo interrupter 10b, which is a pulse pickup, is provided.
This photo interrupter 10b is attached to a roller shaft 5a. That is, a gear 42 that rotates in conjunction with the chain support roller 5 is provided, and a protrusion formed between adjacent gears 42a of the gear 42 is detected by a photo interrupter 10b or other pulse pick-up, and pulses are counted. It is something to do.

According to what is shown in FIGS. 10 and 11, since it is possible to select a finer gear than in the method of counting the rollers of the chain, it is possible to improve the stopping accuracy of the fork pawl portion 2a. In addition, since it detects the protrusion formed between the adjacent teeth 42a of the gear 42, light can be used as the detection part, and the difference in the protrusion can be detected even when electromagnetic pulse pickup is used. 14 and 15 show another embodiment of the present invention. In this embodiment, as shown in FIG. This is intended to correct the error in the chain movement detection signal due to elongation of the chain 6 caused by weight, and a load detector 43 that converts mechanical stress into an electrical signal is inserted in the connecting and fixed part of the chain 6. It is.

For more details, see the mast fixing part 44 and the chain 6.
A load detector 43 is connected between one end of the . As the load detector 43, a load cell, a strain gauge, or the like is used. Further, as shown in FIG. 13, the detection signal from the detection unit 10 is input to the command circuit F, and a correction signal obtained by correcting the load detection signal from the load detector 43 by the correction circuit G is input, and the command circuit F receives the command circuit F. The arithmetic processing section of circuit F performs arithmetic processing to obtain appropriate deceleration command signal _S1 and stop command signal _S2 .

It is assumed that the fork claw portion 2a is stored and set to, for example, the height of the "sixth step" without any load. If the load during subsequent automatic operation is, for example, 2 tons, the chain 6 will stretch elastically due to the load.
Therefore, if the deceleration/stop command is issued by a pulse train in conjunction with the movement of the chain 6, the stop position will shift by the amount of extension of the chain 6.

Therefore, in this embodiment, when the load increases, the tensile force of the chain 6 is detected and a load correction signal is issued. Based on this signal, for example, the deceleration command signal S _{1 is issued at the 180th pulse, and the deceleration command signal S 1} is issued at the 200th pulse. The fork claw part _2a is stopped at a predetermined height by emitting the stop command signal S2, and by emitting the deceleration command signal _S1 at the 182nd pulse and the stop command signal _S2 at the 202nd pulse. It was designed so that

That is, as shown in FIGS. 12 and 13, the output signal S ₃ of the load detector 43 is input to the amplifier 45. The signal input to this amplifier 45 and amplified is input to a first comparator 46a. The comparator 46a compares the amplified signal of the load detector 43 with a reference signal _S0 such as a reference voltage, and when the load on the fork claw portion 2a exceeds a predetermined value, an output signal, that is, a load correction signal _S4 is generated. is input to the command circuit F.

In the command circuit F, the load correction signal _S3 and the detection signal 30 from the detector 10 are processed to generate appropriate deceleration command signal _S1 and stop command signal _S2 .

Note that when the load is, for example, 3 tons instead of 2 tons, the load detection signal _S3 can be further corrected by the second comparator 46b. Also,
If the storage operation is performed with a load applied to the fork, the arithmetic processing unit may be caused to perform an operation opposite to the above when no load is applied.

FIGS. 14 and 15 show still another embodiment of the present invention. In this embodiment, when the mast section is in a tilted state, the operation of the drive control section is stopped or an alarm signal is issued to automatically It was made so that it could not be lifted. That is, in FIG. 14, 47 is a frame, 48 is a support for supporting the mast portion 1, and a micro switch 49 is attached to the tip of the support 48. Furthermore, a protrusion 50 is provided on the outer mast 1a of the mast portion 1 in correspondence with the micro switch 49.
Therefore, when the mast part 1 becomes inclined, the protrusion 5
0 engages with the actuation piece of the microswitch 49, and the microswitch 49 is turned on. The ON signal of this microswitch 49 is used to lock the command circuit F, or to generate an alarm signal by other circuit means (not shown).

FIG. 15 shows a modification of the one shown in FIG. 14, in which a reinforcing piece 51 attached to the upper end of the outer mast 1 is shown.
A pair of contact support pieces 52a and 52b are vertically installed at a predetermined interval, and these support pieces 52a and 52b
Fixed contacts 53a and 53b are fixedly provided at the tips of the contacts 53a and 52b so as to face each other. A flexible lead wire 54 is connected between the contact support pieces 52a and 52b.
A movable contact 53c is vertically provided through the movable contact 53c.

Although these contacts 53a to 53c are not shown, they are connected to a desired control circuit. Therefore, when the mast portion 1 is tilted, the movable contact 53c comes into contact with the fixed contact 52a or 52b due to the action of gravity and is turned on. The ON state of these contacts locks the command circuit F as described above and disables automatic load lifting operation. In other words, automatic load lifting is performed when the mast section 1 is in a vertical or parallel state, and if the mast section 1 is not in a vertical or parallel state, the tip of the fork claw section 2a is not in the specified position, so the automatic circuit is stopped. It is something to do.

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 uses the dead zone setting means to generate a signal corrected for errors caused by the number of pulse signals and the elongation of the string. After performing arithmetic processing with the number of pulses stored in advance by the arithmetic processing section under the condition of the enable signal, a deceleration command is given to the fork drive section and a stop command is supplied to control the moving state of the fork. Therefore, according to the present invention, it is possible to have a forklift automatically and highly accurately load and unload cargo, which is highly effective.

[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.
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 loading device, Figure 10 is a front view of the main part of a modified example, Figure 11 is a side view thereof, Figures 12 and 13 are other implementations. An example is shown in which FIG. 12 is a side view of a main part, FIG. 13 is an electric circuit diagram thereof, and FIGS. 14 and 15 are schematic configuration diagrams of still other embodiments. 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, 42
... Gear, 43 ... Load detector, 47 ... Forklift frame, 48 ... Support, 49 ...
... Micro switch, 50 ... Protrusion, 51 ... Reinforcement piece, 52a, 52b ... Contact support piece, 53a,
53b...Fixed contact, 53c...Movable contact, F...
...Command circuit, G...Load correction 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 drive control unit that controls lifting and lowering operations of the fork, a detection unit that detects the moving state of the string according to the rise of the fork, and a load that detects the weight of the load placed on the fork. a detecting means; a correcting means for correcting a detection error signal of the detecting section due to elongation of the string due to the load of the cargo based on a load detection signal from the load detecting means; a dead zone setting means for generating an enable signal according to a condition; and a detection signal corresponding to the movement of the string from the detection section, which stores a preset moving distance of the fork based on the enable signal from the dead zone setting means. and a command circuit including an arithmetic processing unit that performs arithmetic processing on the correction signal from the correction means to issue a deceleration command for the drive unit and also issues a stop command for the drive unit after a predetermined time; The drive control unit is characterized by comprising a deceleration means for decelerating the driving operation of the drive unit by the deceleration means, and a means for stopping the drive unit by the stop command after the drive unit is decelerated by the deceleration means. Automatic loading device for forklift.