JPH08282994A - Cargo handling control device for forklift truck - Google Patents

Abstract

PURPOSE: To facilitate inching work in a low speed region, by calculating an amount of changing a lift height from a detection signal of a lift height detector, corresponding to a detection signal of turn angle of an operating lever, comparing the change amount with a prestored lift height speed command value calculated, and controlling a current carried in a proportional solenoid control valve by this comparison difference. CONSTITUTION: In a memory 23, a lift speed corresponding to a detection signal of a turn angle detector 12 is set, to store a detection signal in the respective point of detection time of a lift height detector 11, hourly input through an input/output device 21, and the time to the point of present time from lowering down. In a CPU 22, an amount of changing a lift height is calculated from a data stored in the memory 23, and a lift speed value, set corresponding to the detection signal of the turn angle detector 12 in the memory 23, is compared with the amount of changing a lift height to be calculated, to output, as a result of this calculation, a control signal of controlling a level of a current carried in exciting coils 16A, 16B of a proportional solenoid control valve. In this way, regardless of loading weight, a lowering speed is fixed corresponding to a cargo handling operating lever.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling control device for a forklift truck in which a lift descending speed is constant corresponding to a cargo handling lever regardless of load / no-load and a load amount.

[0002]

2. Description of the Related Art Conventionally, a forklift truck equipped with a proportional solenoid control valve for detecting the height of a fork, and a forklift truck having a tilt angle detector for the above-mentioned cargo handling operation lever has a lift descent rate during loading. In order to suppress the above, the flow control valve is further connected to the proportional electromagnetic control valve.

[0003]

As described above, the flow rate control valve is connected to the proportional electromagnetic control valve, and only the maximum flow rate is mechanically suppressed to suppress the lift descending speed at the time of loading. The biggest problem was that inching in the area was difficult. In addition to the proportional solenoid control valve, there is a problem that there is an expensive flow control valve.

[0004]

SUMMARY OF THE INVENTION The present invention is a forklift truck having a proportional electromagnetic control valve and controlling a cargo handling work device by operating a cargo handling operation lever provided on a vehicle body. The forklift truck is arranged in front of the forklift truck. A lift detector that detects the height of the fork, a tilt angle detector that tilts the cargo operation lever, and a detection signal from the lift detector are input to calculate the change in lift, and the calculated lift is calculated. The amount of change in the height is compared with the pre-stored lifting speed command value corresponding to the detection signal from the tilt angle detector, and the difference controls the magnitude of the current flowing to the exciting coil of the proportional solenoid control valve. The present invention has been devised to solve the above problems as a configuration including a control device that operates.

[0005]

1 is a side view showing a counterbalance type embodying the present invention. A counterbalance type forklift 1 includes a vehicle body 2, steering wheels 3 in front of the vehicle body 2, and drive wheels 4 in the rear. A mast 5 is erected in front of the steered wheels 3, and a front hood 6 is formed in front of the vehicle body 2 and behind the mast 5, and a cargo handling operation lever 7 is provided on the upper surface of the front hood 6. A fork 9 is vertically movable via a lift bracket 10 in front of the mast 5.

The mast 5 is composed of an outer mast 5A and an inner mast 5B, and a lift cylinder 8 is arranged behind the outer mast 5A. The lift cylinder 8 is provided with a tilt angle detector 12 and the mast 5 is provided with a lift detector 11. Are arranged.

As shown in FIG. 2, the lift detector 11 includes a chain wheel 1 on the inner mast 5B.
1A is rotatably supported, and the chain wheel 11A
The chain 11B is locked to, and the gear 11C meshing with the chain 11B and the input shaft 11E of the encoder 11D are connected to the input shaft 11E of the encoder 11D meshing with the chain 11B as the inner mast 5B moves up and down. The rotational force is transmitted and the number of rotations of the encoder 11D is counted to detect the amount of rise or fall of the forks 9.

As shown in FIG. 3, the hydraulic circuit includes a tank 13 for storing hydraulic oil, a pump 14 for applying pressure to the hydraulic oil in the tank 13 and pumping it out to the outside, and a hydraulic motor for rotationally driving the pump 14. The hydraulic oil discharged from the pump 14 is supplied to the lift cylinder 8 connected to the proportional solenoid control valve 16 by the conduits 17 and 18, and the lift cylinder 8 applies a driving force for moving the fork 9 up and down. Generate.

The control device 9 comprises an input / output device 21, a CPU 22 and a memory 23, as shown in FIG.

A detection signal from the tilt angle detector 12 and a detection signal from the lift detector 11 are input to the input / output device 21 to control the amount of electricity supplied to the exciting coils 16A and 16B of the proportional electromagnetic control valve 16. A control signal to output is output.

In the memory 23, the ascending / descending speed corresponding to the detection signal of the tilting angle detector 12 is set, and the rising / falling detector 11 is inputted at every moment via the input / output device 21 at each detection time point. The detection signal and the time from the fall to the present time are memorized.

The CPU 22 calculates the amount of change in the elevation from the data stored in the memory 23, and the memory 23
Comparing the set up-and-down speed value corresponding to the detection signal of the tilt angle detector 12 and the amount of change in the above-mentioned elevation,
The exciting coil 1 of the proportional solenoid control valve 16 is calculated by the calculation result.
A control signal for controlling the amount of electricity supplied to 6A and 16B is output.

[0013]

As described above, according to the present invention, the lift descending speed becomes constant corresponding to the loading / unloading operation lever regardless of the load / no load and the applied load amount. Since a control valve is unnecessary and an expensive flow rate control valve is not used, there is an effect that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side view showing a counter balance type embodying the present invention.

FIG. 2 shows a side view of a lift detector.

FIG. 3 shows a hydraulic circuit diagram.

FIG. 4 shows a block diagram of a control device.

[Explanation of symbols]

 1 Counterbalance type forklift 2 Body 3 Steering wheel 4 Drive wheel 5 Mast 6 Front hood 7 Cargo handling lever 8 Lift cylinder 9 Fork 10 Lift bracket 11 Lifting height detector 13 Tank 14 Pump 15 Hydraulic motor 16 Proportional electromagnetic control valve 20 Control device

Claims (1)

[Claims] 1. A lift truck for controlling a cargo handling device provided with a proportional solenoid control valve for controlling a cargo handling operation device provided on a vehicle body, for detecting a height of a fork arranged in front of the forklift truck. A high detector, a tilt angle detector for the cargo handling lever, and a detection signal from the lift detector are input to calculate a change in lift, and the calculated change in lift and tilt angle are detected. A fork equipped with a control device that performs a comparison calculation with a pre-stored lifting speed command value corresponding to the detection signal of the controller and controls the magnitude of the current supplied to the exciting coil of the proportional solenoid control valve by the difference. Lift truck cargo handling control device.