JPS5982298A - Method of automatically stopping fork in forklift truck - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] The present invention is a microcomputer that stores data such as the height of the cargo platform and the height of the cargo seat, and automatically controls the lifting height of the forks. In particular, we are concerned with an automatic fork stop method that allows cargo handling operations to be carried out without the need to change data input to the microcomputer even when the height of the loading platform or the height of the cargo being handled changes. It is something.

Conventional forklifts using microcomputers store data such as the height of the cargo platform and the height of the cargo seat in the microcomputer to assist the driver's driving skills and to enable even unskilled workers to perform cargo handling operations easily. A forklift (hereinafter referred to as a microcomputer lift) that raises or lowers its fork to a predetermined height by pressing a button, and a self-driving vehicle that is controlled from a ground station using a guide line. forklifts (hereinafter referred to as unmanned lifts).

Since both microcomputer lifts and unmanned lifts have almost the same structure and function in terms of fork elevation control, the conventional σ) unmanned lift cargo handling work will be explained below.

To explain the work steps of so-called stacking work, in which multiple loads are stacked and placed on the floor using a conventional unmanned lift, It will be transported using an unmanned lift.

■ Lower the fork and bring the bottom of the pallet into contact with the floor.

■ Roughly lower the fork by the specified amount.

■ Stop the fork at the middle position between the top and bottom of the pallet hole.

■ Move the unmanned lift backwards and remove the fork from the pallet.

■ The second load is transported by an unmanned lift so that it corresponds to the top surface of the first load.

■ Lower the fork and bring the bottom of the pallet into contact with the top of the first load.

■Further lower the fork by a predetermined amount.

■ Stop the fork at the middle position between the top and bottom of the pallet hole.

@) Put the forklift in reverse and pull out the make-up from the pallet.

The work steps are as follows.

Here, if the work of stopping the forks at the upper and lower intermediate positions of the pallet holes is not accurately controlled as in steps ■ and step ■, the forks may come into contact with the pallet when the unmanned lift moves backwards, causing the load to collapse. Therefore, in conventional equipment, data such as baggage, B'6 size, etc. are accurately recorded (this microcomputer is used by two people to prevent the load from falling apart).

However, with such conventional unmanned lifts, it is necessary to re-enter the input data to the microcomputer each time there is a change in the height of the cargo in order to prevent the cargo from shifting. Random stacking of multiple packages with varying heights was completely impossible.

The purpose of the invention is to provide a method for automatically stopping a fork that eliminates the disadvantages of the conventional device. The output of the pressure switch is outputted to the control device O, and when the pressure switch is turned off during the lowering operation of the fork, the control device This is a method that allows the fork to stop at an intermediate position above and below the pallet hole after continuing its downward movement.

Embodiment 2 of the invention will be explained below with reference to the drawings.

In the figure, (1) is the front wheel (2) and rear wheel (3), and (4) is the front wheel (1) of the garage frame (1), which is rotatably supported. The tilt cylinder (5) (a mast device that tilts forward and backward, (6) Huff 7) is supported by the device (4) so that it can be raised and lowered, and by the operation of the lift cylinder (7), the chain wheel (8) and The fork is moved up and down via the chain (9), and (Jo) is a rotary encoder that constitutes a fork lift height sensor that detects the amount of rotation of the chain wheel (8) via the input shaft (IOA). Furthermore (11)
is a control device including a microcomputer disposed in the second part of the garage frame (1), and is configured in the same way as a conventional unmanned lift and has the same functions as No. 1-1i71.

As shown in the hydraulic/electrical circuit diagram in Figure 6, the essential structure of the invention is to install a pressure switch θ2) on the cylinder bottom side of the lift cylinder (7) and control the output of this pressure switch. This circuit is configured to input data to the device (11), and the circuit diagram will be described in detail below.

In the figure, (13) indicates that the hydraulic oil in the hydraulic oil tank (T) is sucked in through the suction pipe (14), and the solenoid valve (16) for the lift cylinder and the solenoid valve (16) for the tilt cylinder are sucked in through the suction pipe (14). This is a hydraulic pump that supplies hydraulic pressure to the solenoid valve (17), and is connected to the cylinder bottom chamber (7A) of the lift cylinder (7) via the lift cylinder solenoid valve 06) and the lift pipe line 08), and is connected to the cylinder bottom chamber (7A) of the lift cylinder (7). Valve 07) is connected to the tilt pipe (
19A).

(i 9 E) respectively to the 2t piston rod chamber (
5A) and the cylinder bottom chamber (5B) are connected.

Also, each solenoid valve θG) (+7) and tank (
T) is connected to the return pipe (31), and the discharge pipe (15) is connected to the relief valve (2 (+>
The relief conduit ψ containing the pipe is connected by a relay.

Note that \(16A) is a stopper that limits the descending speed of the lift cylinder (7).

The pressure switch (12) is connected to the lift pipe (+8), and its output is input as an ON/OFF electric signal to the control device (11) through a wire.

Other input signals to the control device (II) include the lift signal input from the rotary encoder θ0) via the wiring (c), and the output signal of the control device (11) is
Solenoid (2 → (29) for operating each solenoid valve (+6) Cl7) through 2
) H(:u)p inputs 0 Next, the operation of the uninvented device constructed in this way is shown in the hydraulic/electrical circuit diagram in Fig. 6, the action explanatory diagram in Fig. 4, and Fig. 5. Flowchart II will be explained below.

Now, as shown in FIG. 4, we will sequentially explain the stacking operation in which Zara G and other packages are stacked directly on top of the package (V/1).

■ When the lowering process of the fork (6) starts from the state shown in Fig. 4 (a), the solenoid (29) of the lift cylinder solenoid valve (16) is activated by the control device (11).
), and the solenoid valve +6) is (
1) Position M, & is switched so that the pressure oil in the cylinder bottom chamber (7A) of the lift cylinder (7) is returned to the return pipe (32).
) to the tank (T), and the fork (6)
begins to descend.

■ At this time, the pressure inside the lift pipe (12) is high due to the load QJ2 being placed on the fork 2 and the action of the throttle (16), and the pressure switch (12) is turned ON. There is.

■ The control unit W (II) judges whether the input of the pressure switch (2) is ON or OFF, and if it is ON, continues to issue a descending command. (Continue energizing the solenoid (29).) ■ The fork (6) is lowered and the state shown in Figure 4 (b) is reached, the load (Wl) with the bottom of the pallet (T) (P) placed on the bottom. When it comes into contact with the top surface of
P)-1: The weight of the load (W2) is the weight of the load (Wl)
Since it is supported by the lift pipe (7), the pressure becomes low and the pressure switch (I2) becomes 0 plate.

■ When the pressure switch (12) turns OFF, the control device ft.
(+1) is a fork (6) placed in the middle position above and below the pallet hole.
-1 of the input of the rotary encoder (10) and the vertical spacing of the pallet holes input in advance until .
0 ■ Fork (
When the fork (6) reaches the lower intermediate position of the position shown in FIG. To be more specific, the solenoid (29) is de-energized and the solenoid valve (16) is switched to the neutral position (N), whereby the oil flowing back from the lift cylinder (7) to the tank (T) is switched to the neutral position (N). Block the flow O ■ From this state, the unmanned lift truck moves backwards and completes the stacking work.

As mentioned in 2.9, the uninvention is to install a pressure switch on the cylinder bottom of the lift cylinder, and
The output of the pressure switch is output to the control device, and during the lowering operation of the fork, after the pressure switch is turned OFF, the lowering operation of the fork is continued by a predetermined amount, and then the fork is automatically moved to the double intermediate position of the pallet hole. The fork can be stopped at a position halfway between the top and bottom of the pallet hole, even if the height of the load changes, which has the effect of greatly improving the safety of cargo handling operations. Then [
This has the effect that the height of the load placed on the rack changes depending on the weight Q of the load, making it possible to perform the stacking work extremely well.

Furthermore, by using a pressure switch, the generated νj becomes more reliable than a mechanical sensor that detects whether there is a load on the fork using a lever or a mito switch.

In the above-described embodiment, the fork is stopped by a predetermined amount from the time when the pressure switch is turned off, but the control is also performed after a predetermined time delay as shown in the flowchart of FIG. It is also possible.

[Brief explanation of the drawing]

The figures show an embodiment of the invention, and the first figure is a complete side view, and the second figure shows an embodiment of the invention.
The figure is a partial rear view showing the installation state of the row encoder.
Figure 6 is a hydraulic/electrical circuit diagram, Figure 4 is an explanation diagram of the function, and Figure 5 is a hydraulic/electrical circuit diagram.
The figure is a flowchart showing the operation of the control device. Further, FIG. 6 is a flowchart corresponding to FIG. 5 showing another modification example. (6)...Fork, (7)...Lift cylinder,
(8)...Chain wheel, (1o)...Lower encoder ~ (11)...Control device, (12)...
・Pressure switch, (13)...Hydraulic pump, 06)・
...Solenoid valve for lift cylinder, (T)...
Hydraulic oil tank - (P)...Pallet, (Wl) (W
2)...Luggage patent applicant Toyota Industries Corporation representative Patent attorney Kitao Matsuura

Claims (1)

[Scope of Claims] A switching valve that controls supply of pressure oil supplied by a hydraulic pump from a hydraulic oil tank to a lift cylinder or discharge of pressure oil in the lift cylinder to the hydraulic oil tank, and the amount of elevation and descent of the fork. A forklift truck equipped with a lift height sensor that detects a lift height sensor and a control device that controls switching operation of the switching valve based on the output of the lift height sensor and a command from a microcomputer, a pressure switch is provided on the cylinder bottom side of the lift cylinder. 2, the output of the pressure switch is input to the control device, and when the pressure switch is turned OFF during the lowering operation of the fork, after the pressure switch is turned OFF by the control device. 1. A method for automatically stopping a fork in a forklift truck, characterized in that the switching valve is switched and controlled after a predetermined amount of lowering of the fork continues, and the fork can be controlled to stop at an intermediate position of an upper die of a pallet hole.