JPH0633159B2 - Fork lift controller for forklift trucks - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fork lift control device for a forklift truck.

(Prior Art) As the number of rack beams (shelves) for loading luggage increases in a warehouse, the fork lift of a rack forklift truck for loading and unloading the luggage on a pallet increases significantly. It is structured so that it can descend.

It is extremely difficult to manually enter and leave the rack forklift truck that moves up and down in this way.
There are known automatic or semi-automatic ones. Therefore, in the conventional fork lift control device, limit switches are provided on the masts of forklift trucks corresponding to the heights of the rack beam stages, and the lift signal of the limit switches controls the fork lift. It was

However, the height of the fork when loading and unloading the same beam as the rack is higher when loading (unloading) than when loading (unloading) because the fork is inserted into the hollow pallet, and the fork is raised and lowered. Since it is necessary to perform high speed and low speed variable speed control in order to speed up the operation, a large number of limit switches are required for each stage,
Therefore, the adjustment and the setting change are not easy. By the way, this is a semi-automatic control by limit switch, and the number of limit switches required for each stage is 2 for each of up and down stop, 1 for up and down deceleration, and 1 for down and down deceleration, for a total of 6 .

A device using a microcomputer that receives a pulse signal from a sensor that detects the lift of a fork and outputs a control signal for automatic lift operation has also been proposed (for example, JP-A-57-170399). reference). However, even in a control device using this type of microcomputer, if the fork is repeatedly raised, lowered, and stopped a considerable number of times, an error in the count value by the lift detection sensor often occurs due to the influence of the mechanism, If accumulated, control accuracy may be degraded. Further, in a control device using such a microcomputer, in order to automatically control the lift of the fork, it is necessary to set and store the lift for each stage of the rack beam at the initial stage of use, It has been desired to realize an apparatus that facilitates this work.

(Object of the Invention) The present invention solves the above-mentioned problems, and can prevent the cumulative error due to the lift detecting means from occurring, and further,
An object of the present invention is to provide a fork lift control device for a forklift truck that does not require a large number of limit switches for each stage of the rack, and that facilitates work for setting, adjusting, and changing settings of each stage of fork lift. And

(Structure of the Invention) The present invention is based on an operating mechanism for moving a fork up and down, a lift detecting means for detecting a lift of the fork, and the above-mentioned operation based on the lift detecting means and operation command signals of various push buttons of the operating section. In a fork lift control device for a forklift truck equipped with a control unit that outputs a control signal to the mechanism, a lower limit switch and an intermediate limit switch that detect the lower limit position of the fork and the midpoint height of the lift are arranged. However, the control unit corrects the value detected by the lift detecting means to 0 when the operation signal of the lower limit switch is received, and also as the intermediate point when receiving the operation signal of the intermediate point limit switch. It has a function of correcting to a predetermined elevation value set in advance.

Further, the control unit is provided with a storage means for storing the step-set lift value, and sets the stored lift value at the time of entry or exit to the set value, and calculates the other lift value and the inching up / down value of the fork. Thus, it is possible to have a function of automatically setting and storing in the storage means.

With this configuration, the detection value of the fork height is forcibly preset at the lower limit lowering position and the intermediate point position during the fork raising / lowering operation, and the accumulated error of the detection value does not occur. In addition, the lift value setting work for each stage can be performed by simply setting the lift value at the time of leaving or entering the warehouse, and the operation becomes easy.

(Embodiment) FIG. 1 shows a schematic construction of a forklift truck according to an embodiment of the present invention, and FIG. 2 shows a construction of a fork lift control device of the forklift truck.

In these figures, 1 is a forklift truck main body, 2,
3 is a fixed outer mast for lifting the fork and inner mast guided by the outer mast, 4 is a lift hydraulic cylinder that drives the inner mast 3 to move up and down, 5 is a fork that moves up and down guided by the inner mast 3, and 6 is the upper end of the inner mast 3. , One end of which is connected to the fork 5 and the other end of which is connected to the lower portion of the outer mast 2, and the middle portion of which is the pulley 6
It is a chain hung on.

The fork elevating mechanism 20 is configured as described above, and when the inner mast 3 and the pulley 6 are moved up and down by the tip of the piston rod by the operation of the lift hydraulic cylinder 4, the fork 5 is moved by the action of the chain 7 and the pulley 6 so that the stroke of the piston is blocked. Move up and down by a length that is twice the amount of movement of the inner mast 3. The outer mast 2 is provided with an encoder pulley and an encoder 8 at the upper end thereof, while the inner mast 3 is provided with an encoder chain 9 which engages with the encoder pulley, by which the lift of the fork is detected. It constitutes the mechanism.

Further, the lower limit switch 10 and the intermediate limit switch 1 for detecting the lower limit position of the fork and the intermediate point height at the lower end portion and the intermediate portion of the outer mast 2, respectively.
On the other hand, the inner mast 3 is provided with an operating piece (dog) 12 which engages with the limit switches 10 and 11 to operate the limit switches 10 and 11.

Further, the main body 1 includes an operation unit 21 operated by an operator, a microcomputer for controlling the lifting operation of the fork based on a command from the operation unit 21 and signals from the encoder 8 and each of the limit switches 10 and 11. And a hydraulic control unit 23 for controlling the operation of the elevating mechanism 20 based on the output signal of the control unit 22, and an operating mechanism for elevating the fork by the elevating mechanism 20 and the hydraulic control unit 23. It is configured.

In FIG. 1, h indicates the actual lift of the fork, which is detected by the encoder 8. Further, h ₀ and hx represent the operating regions of the lower limit switch 10 and the intermediate point limit switch 11.

Next, specific configurations of the operation unit 21, the control unit 22, and the hydraulic control unit 23 will be described with reference to FIG.

The operation panel 24 of the operation unit 21 has a plurality of rack shelves (1 to 6 here) at the time of loading (loading) and unloading (loading).
And push buttons 25 and 26 for setting and designating the rack, a push button 27 for switching the row (A, B) of the rack, a semi-auto push button 28 and a full-auto push button 29 for starting the fork lifting operation, and a semi-auto push button. A push button 30 for inching the fork and a stop push button 31 are provided.
Further, when the panel of the operation panel 24 is opened, a step memory push button 3 for initial setting of the step lift is provided on the inner operation box surface.
Two are provided. The procedure for these operations will be described later.

The microcomputer constituting the control unit 22 receives the operation command signal from the control unit 21 and the detection signals from the encoder 8 and the limit switches 10 and 11, and performs a predetermined process described later based on the signals. , Hydraulic control unit 2
A control signal is output to 3. Further, this microcomputer includes means 33 for storing the step height setting value, means 34 for presetting the lift detection value of the fork by the encoder 8 when the lower limit switch 10 and the intermediate point limit switch 11 are operated, and each step. For each of the functional means of the setting means 35, by storing the set lift value for either the storage or the discharge, the other lift value and the fork lift value of the fork are automatically set and stored in the storage means 33. I have it.

The hydraulic control unit 23 has an electric circuit which is operated by the output from the control unit 22 and a hydraulic circuit which is operated by a command from the electric circuit. The electric circuit includes a power source E and a hydraulic motor as shown in the drawing. Armature A, winding W, resistance R for speed control, electromagnetic relay M1 for hydraulic motor drive and its relay contact CM1, electromagnetic relay M2 for high speed drive of hydraulic motor and its relay contact CM2 Solenoid SOL for switching hydraulic circuit between automatic and manual
1. Solenoids SOL2 and SOL3 for switching the hydraulic circuit at the time of lowering the lift between low speed and high speed. On the other hand, the hydraulic circuit includes a hydraulic pump P driven by a hydraulic motor,
A valve driven by the solenoids SOL1 to SOL3,
It includes check valves V1 and V2, variable throttles S1 and S2, a manually operated hydraulic circuit MC, and a tank T.

Then, when the fork (lift) is raised at high speed, the electromagnetic relays M1 and M2 and the solenoid SOL1 are turned on.
Then, the resistor R is short-circuited by the contact CM2 to rotate the hydraulic motor at high speed to supply the lift hydraulic cylinder 4 from the hydraulic pump P through the check valve V1, and at the time of low speed, only the electromagnetic relay M1 and the solenoid SOL1 are turned on, The hydraulic motor is rotated at a low speed to supply oil to the cylinder 4 through the same passage as above.

On the other hand, when the fork is descending at high speed, the solenoids SOL2, 3 are turned on to discharge the oil from the cylinder 4 to the tank T through the throttle S1, and at low speed, only the solenoid SOL2 is turned on and the throttle S2 (from the throttle S2 Oil is discharged to the tank T through a large throttle. The check valve V2 serves as a passage for discharging oil when the lift is manually lowered by using the manually operated hydraulic circuit MC. By switching between low speed and high speed, the speed of operation and the impact at the time of stopping can be weakened.

FIG. 3 shows that each rack rack has a single row 41, 42, 43.
It shows the relationship of fork lift when leaving. In the figure, L
Is a pallet on which the luggage L is placed, and the fork tip is inserted into the hollow portion of the pallet PA for loading and unloading. It will be different. Line H1, H
2, H3 is the set height of the fork at the time of shipping in each stage,
Lines H1u, H2u, H3u indicate the set heights of the forks at the time of warehousing in each stage, and the difference in height between the stages is usually 100 to 200 mm. From these set heights, it is necessary to further perform the inching operation, which will be described later, for the fork in order to carry out and store.

FIG. 4 shows pulse output signals from the encoder 8 during rising and falling, and this pulse output signal
The phase A output is faster than the phase B output by 90 °, and
At the time of falling, the phase A output is delayed from the phase B output by a phase difference of 90 °. Due to this difference in phase difference, the control unit 2
In 2, pulse is added when rising (up count)
However, the lift of the fork is detected by subtracting (down-counting) the pulse when descending.
It should be noted that the number of pulses may be such that one pulse is output per 1 mm stroke of the fork.

FIG. 5 is a flowchart showing an initial setting procedure for presetting a lift detection value when the limit switch is operated. Explaining the procedure of this initial setting, first, while continuously pressing the step memory push button 32 (FIG. 2) (step S ₁ ), the fork 5 is lowered to the lower limit to the full limit (step S ₂ ), and the lower limit switch 10 is operated. when (step _S 3), preset to "0" detection value h by the encoder 8, which memory (step _S 4). Next, the fork 5 is raised (step S ₅ ), and when the intermediate point limit switch 11 is activated (step S ₆ ),
Detection value h of the "X" (X is the value that is set in advance as the midpoint, for example, 1500 mm) preset, this similarly memory (step S _7). With the above, the initial setting is performed, and the functional operation is enabled by the presetting means 34. In the subsequent operation, the detection value can be preset when each of the limit switches 10 and 11 operates.

FIG. 6 is a flowchart showing a procedure for initial learning (teaching) of setting for each stage of fork lift. This learning procedure will be described. First, the fork 5 is moved to the desired step height (step S ₁₁ ) and the step setting push button 26 (FIG. 2) on the unloading (loading) side is pressed (step S ₁₂ ). Next, by instructing a row (step S ₁₃ ), and further pressing the step memory push button 32 (step S ₁₄ ), the detected value h at this time is set as a step set height Hn (n is a step number) in the storage means. 33 to the memory (step S _15). In addition, in the operation panel 24 of FIG.
Only one 7 is provided for selecting the B row, and the push button 27 is not pressed when the A row is selected. The number of rows may be three or more.

In this way, when the height of each stage at the time of warehousing is set (H1, H2, H3, etc. described above), the setting means 35 in the control unit 22 and the processing automatically carry out warehousing (loading). ) Hour height (H1u, H2u, H3u, etc.) is set,
Further, the height Hn + C during inching (C is the inching distance) is set.

Figures 7 (a) and (b) show semi-automatic loading at the start of the fork, and inching movements at loading, and Figures 8 (a) and (b) show full-automatic loading. , Shows movements including fork shift (feeding and feeding) operations during loading. In these figures, the numbers 1 or 1 ', 2, 3, 4
Indicates the order of movement.

FIG. 9 is a flowchart showing the fully automatic operation of the above control device. This operation will be described with reference to the same figure. First, each push button on the operation panel 24 is used to give instructions for loading, unloading, rack rows, and fork left and right directions (not shown in FIG. 2). Perform (step S ₁ ). If the instruction is a shipping instruction, the control unit 22 determines the stage setting storage height H
The n and instructs the height H, (in this case it is a 100mm inching distance C) stage setting storage height Hn + 100 if loading instruction and instructs the height H (the step S ₂₂ ~S _24). The indicated height H is compared with the detected value (current height) h at the present time by the encoder 8 (step S ₂₅ ). If the indicated height H is larger than the current height h, the lift is raised at high speed. and performed (step S _26), instructs the height H- current height h 10
If it is within 0 mm, the lift rise is switched to a low speed (steps S ₂₇ and S ₂₈ ). Then, if the indicated height H becomes equal to the current height h, the lift is stopped (steps S ₂₉ and S).
₃₀ ).

Then it performs a shift delivery operation (Step S _31), followed by shifts dimensioned operation (step S _32). In this inching operation, if the instruction is out product instruction, 'it indicates the H + 100 mm as (step S _34), inching rise height H' inching rise height H to equal current to the height h perform lift raising at a low speed (step _35, S _36), to stop the lift if the H '= h, followed performs a shift retracting operation (step S _37, S _38), the operation ends.

Further, also indicated the height H is greater than the current height h, when there is no equal, that is, when an instruction height H is now smaller than the height h (NO in Step S _25, S _29), the lift lowering performed at high speed (step S _39), if the current height h- instruction height H within 100 mm, switching the lift lowering in low speed (step S _40, S _41). When H = h, the lift is stopped (step S ₃₀ ), and the same steps as above are executed.

Further, in the inching operation, instruction is not an instruction output product, when the loading instruction, 'instructs the H-100 mm as (step S _42), inching down the height H' inching lowered height H The lift is lowered at a low speed until it becomes equal to the current height h (S ₄₃ ,
_S44 ) and when H '= h, the lift is stopped (step S
₃₇ ), and then the same steps as above are executed to end the operation.

As described above, loading and unloading, lift up and down, and high speed and low speed judgment control are executed. Then, during this operation, when the lower limit switch 10 and the intermediate point limit switch 11 are activated, the lift detection value by counting the number of pulses from the encoder 8 is forcibly preset, so that the accumulated detection value is accumulated. The error is removed. In particular, since detection by counting the number of pulses from the encoder is relative position detection, it is significant to introduce the absolute position at an appropriate time point by forcibly presetting it.
Moreover, the middle point position is a point where the fork frequently passes, and is effective for error removal.

It should be noted that the number of required limit switches is smaller than that of the conventional device having a large number of limit switches, so that the field of view in front of the mast when driving the fork is good, and the driving operability is also improved. You can

(Effect of the invention) As described above, according to the invention of claim 1, when the lower limit switch and the intermediate limit switch are operated, the detection value by the lift detecting means is forcibly preset. The accumulated error of the detected value is removed, and the fork lift control with high accuracy becomes possible. In particular, since the intermediate point limit switch is in a position where the pass rate is high during normal use, the cumulative error prevention effect is great.

Further, according to the invention of claim 2, if the lift value at the time of entering or leaving is set as the set value, the other lift value is automatically set and stored in the storage means. It is easy to set up, adjust and change the settings.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a forklift truck according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a forklift height control device of the lift truck, and FIG. 3 is a rack and a fork at the time of loading and unloading. FIG. 4 is a relational diagram of the elevation, FIG. 4 is a detection signal waveform diagram of the encoder as the elevation detection means, FIG. 5 is a flow chart showing the procedure of the initial setting of the preset for the lower limit and the intermediate point, and FIG. Fig. 7 (a) (b), Fig. 8 (a) and (b) show the initial learning procedure, and Fig. 7 (a), (b) and Fig. 8 (a), (b) show the movement of the fork during the semi-automatic and full-automatic operations, FIG. 9 is a flowchart showing the operation of the control device. 1 …… Forklift truck body, 5 …… Fork, 8 ……
Encoder (lift height detecting means), 10 ... Lower limit switch, 11 ... Intermediate point limit switch, 20 ... Lifting mechanism, 21 ... Operation part, 22 ... Control part, 23 ... Hydraulic control part, 25, 26 ... Pushbuttons for loading and unloading,
28, 29 ... Start push button, 31 ... Stop push button,
32 ... Step memory push button, 33 ... Storage means, 34 ... Preset means, 35 ... Setting means.

Claims (2)

[Claims] Claim: What is claimed is: 1. An operating mechanism for raising and lowering a fork, a lift detecting means for detecting lift of a fork, and a control signal to the operating mechanism based on operation command signals of the lift detecting means and various push buttons of an operating section. In a fork lift control device for a forklift vehicle equipped with a control unit for outputting, a lower limit limit switch and an intermediate limit switch for detecting the lower limit position of the fork and the intermediate point height of the lift are arranged, and the control is performed. The section corrects the value detected by the lift detecting means to 0 when it receives the operation signal of the lower limit switch, and presets it as an intermediate point when it receives the operation signal of the intermediate point limit switch. A fork lift control device for a forklift truck, which has a function of correcting to a predetermined lift value. 2. The control unit is provided with a storage means for storing the step-set lift value, and sets the stored lift value at the time of entry or exit to the set value, and the other lift value and the inching of the fork. The fork lift control device for a forklift truck according to claim 1, having a function of automatically setting a value by calculation and storing it in the storage means.