JPH05238694A - Forklift control device - Google Patents

Abstract

PURPOSE:To prevent the generation of a human accident by providing a control means for computing moment from the detection value of an oil sensor and a stroke sensor to compare this moment with the fixed value and stopping the driving of a side shift cylinder at the time of the moment exceeding the fixed value. CONSTITUTION:A forklift is constructed in such a way that a fork is elevated along an outer mast by the driving of a lift cylinder 1 and also the whole fork is moved laterally by a side shift cylinder 28. A forklift control device is provided with an oil pressure sensor 23 for detecting load on the fork, and a stroke sensor 24 for detecting the lateral moving quantity by the side shift cylinder 28. From the detection value of the oil pressure sensor 23 and stroke sensor 24, moment is computed and compared with the fixed value, and when the moment exceeds the fixed value, the driving of the side shift cylinder 28 is stopped by a control circuit 20. No more side shift is thereby performed to prevent overturning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift control device for a forklift, which is a side-shift type fork which allows the fork to move laterally.

[0002]

2. Description of the Related Art A forklift truck is an industrial vehicle for loading and unloading, which is provided with a mast for raising and lowering loaded loads in front of a vehicle body so that it can be moved from place to place.

FIG. 4 is a perspective view showing an example of a standard forklift. As shown in the figure, the lift cylinder 1
Is fixed to the pair of left and right outer masts 2, and the pair of left and right inner masts 3 is moved up and down with the outer mast 2 as a guide as the piston rod 1a expands and contracts. At this time, the outer mast 2 is fixed to the vehicle body 4 in front of the vehicle body 4. As a result, the inner mast 3
Along with the lifting and lowering, the lifting and lowering unit including the bracket 5 suspended on the chain (not shown) and the forks 6 for directly loading luggage is lifted and lowered.

Although the forklift described above is of a standard type, this forklift is generally adapted to be equipped with various attachments adapted to the shape of the load to be conveyed. There is a side shift function as a kind of this kind of attachment.

The side shift function is a function of moving the entire lifting portion of the bracket 5 and the fork 6 in the left-right direction, and the entire fork 6 is moved in the arrow direction by driving a side shift cylinder (not shown in FIG. 4) ( Shift). With this side shift function, the forks 6 can be easily positioned when loading or unloading luggage, and stable unloading is possible.

However, when handling such a side-shift type forklift, when the rated load is applied while the sideshift is moved to the stroke end, depending on the lift amount of the fork 6 and / or the vehicle body based on the unevenness of the floor. Depending on the inclination of the forklift, the forklift may fall over.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a forklift control device which eliminates the risk of the forklift falling due to side shift.

[0008]

According to the present invention for achieving the above object, the fork is moved up and down along the outer mast by driving the lift cylinder, and the entire fork is moved left and right by driving the side shift cylinder. In the forklift truck, a hydraulic sensor for detecting the load on the fork and a stroke sensor for detecting the lateral movement amount by the side shift cylinder are provided, and a moment is calculated from the detection values of the hydraulic sensor and the stroke sensor to obtain a constant value. In comparison with, a control means for stopping the driving of the side shift cylinder when the constant value is exceeded is provided.

[0009]

When the moment exceeds a certain value where there is a risk of tipping, even if a side shift drive command is generated, it is eliminated and the side shift cylinder drive is stopped, so that a further side shift is performed. The fall is prevented.

[0010]

EXAMPLES Examples of the present invention will now be described with reference to FIGS. FIG. 1 is a block diagram showing a system configuration, and mainly shows a control circuit of an input / output unit related to side shift and lift of the present embodiment. The control circuit 20 includes clocks 20b, RA centering on the CPU 20a.
M / ROM storage device 20c, output driver electromagnetic valve drive circuit 20d, input side digital conversion unit A /
It has a D converter 20e and the like.

Of these, the A / D converter 20e is connected to an up / down operating lever 21 for driving a lift cylinder for raising and lowering a fork, and a left / right operating lever 22 for driving a cylinder for side shift, and also on the fork. A hydraulic sensor 23 for detecting a load and a stroke sensor 2 for detecting a piston movement amount of a side shift cylinder.
4 is connected.

On the other hand, as outputs, electromagnetic control valves 25a and 25b for shift cylinder control and electromagnetic control valves 26a and 26b for side shift cylinder control are connected to an electromagnetic valve drive circuit 20d. Of these, the control valve 25a is for raising, 25b is for lowering, the control valve 26a is for right side, 26
b is for the left side.

FIG. 2 mainly shows the hydraulic circuit based on the configuration shown in FIG. In the hydraulic circuit, hydraulic pipes are formed using an engine-driven hydraulic pump 27 as a hydraulic source, communicate with the lift cylinder 1 through electromagnetic control valves 25a and 25b, and further through hose reels and electromagnetic control valves 26a and 26b. It is connected to the side shift cylinder 28 via a junction block. In this case, since the side shift cylinder 28 is mounted on the mast or the like, the side shift cylinder 28 is movably attached to the vehicle body 4 itself (see FIG. 4), and therefore a hose reel or the like is provided as a pipe. In FIG. 2, each electromagnetic control valve is in the neutral position.

The control circuit 20 is connected to the up / down operating lever 21 and the left / right operating lever 22, and is connected to the anti-piston rod side of the lift cylinder 1 to detect a hydraulic pressure corresponding to the load and a side shift cylinder 28. Stroke sensors 24 connected to the piston rods for detecting the amount of movement of the piston rods are electrically connected.
Further, from the control circuit 20, the electromagnetic control valves 25a, 25
There are connections to control b, 26a, 26b.

With such a structure, the vertical operation lever 21
When the solenoid control valve 25a or 25b is turned on to supply or discharge the hydraulic pressure to the lift cylinder 1, the lift cylinder 1 is vertically driven. Further, by operating the left and right operation levers 22, the electromagnetic control valve 26
side shift cylinder 28 when a or 26b is thrown in
The hydraulic pressure is supplied to the side opposite to the piston rod or the side of the piston rod to perform the side shift.

FIG. 3 is a side shift control flow performed by the control circuit 20, which has a fall prevention means. In FIG. 3, after initialization, block A determines whether the side shift is to the right. Next, blocks B and C
As a result, the shift position and the neutral value are subtracted from each other, and a negative value is obtained in block B when moving rightward, and a positive value is obtained in block C when moving leftward. The blocks B and C detect whether or not the shift is in progress. When the shift is not in progress, the shift right lever output calculation (block D) or the shift left lever output calculation (block E) is performed. Also, when the blocks B and C are being shifted,
At blocks F and G, the moment is calculated by multiplying the shift amount by the load and comparison with a constant value (threshold value) is performed. If this constant value exceeds a certain moment, there is a risk of a fall, so the moment of the fall limit is applied for the judgment. If the shift amount and the moment due to the load are above a certain value, there is a risk of falling, so the shift right lever output is set to zero or the shift left lever output is set to zero (blocks H and I). .. Thus, when the shift right lever output calculation and the shift left lever output calculation are performed in blocks D and E, the solenoid valve output is controlled according to the calculated values (block J). If the output is zero in blocks H and I, the solenoid valve output is controlled to the neutral position and the shift is stopped.

[0017]

As described above, according to the present invention, when the fall moment is approaching, the side shift is automatically prevented from further increasing, so that there is no possibility of the fall to the side due to overshift, resulting in a personal injury. The occurrence can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a mechanism of the embodiment.

FIG. 3 is a control flowchart.

FIG. 4 is an overall configuration diagram of a forklift.

[Explanation of symbols]

 1 shift cylinder 20 control circuit 20a CPU 21 up / down operating lever 22 left / right operating lever 23 hydraulic sensor 24 stroke sensor 25a, 25b, 26a, 26b electromagnetic control valve 28 side shift cylinder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Matsuda 3000 Tana, Sagamihara-shi, Kanagawa Mitsubishi Heavy Industries, Ltd. Sagamihara Works (72) Inventor Toshiyuki Midorikawa 3000, Tana, Sagamihara, Kanagawa Eye Sagami High-Tech Co., Ltd. (72) Inventor Tsuruji Kitabayashi 3000 Tana, Sagamihara-shi, Kanagawa M-E-I Sagami Hi-Tech Co., Ltd.

Claims (1)

[Claims] 1. A hydraulic sensor for detecting a load on the fork in a forklift in which a fork lifts up and down along an outer mast by driving a lift cylinder and the entire fork moves left and right by driving a side shift cylinder. And a stroke sensor that detects the amount of lateral movement by the side shift cylinder, calculate the moment from the detection values of the hydraulic pressure sensor and the stroke sensor, and compare the moment with a constant value. A control device for a forklift, comprising a control means for stopping driving.