JPH08282997A - Cargo handling control device for forklift truck - Google Patents

Abstract

PURPOSE: To improve workability in a slow speed region by setting a target value of exciting current flowing in a proportional solenoid control valve by an angle of an operating lever, comparing the target value with a command value of presetting an opening area of the control valve, and carrying the current without a time delay in the case that the target value is smaller than the command value. CONSTITUTION: In a conventional cargo handling control device, a current is carried in a proportional solenoid control valve with a time delay from the standpoint of preventing an accident such as collapsing a cargo. Here in the control device, a target value of exciting current flowing in an exciting coil of the proportional solenoid control valves 15, 16 is set by an operating angle of a lift operating lever 8, to compare this set target value with a command value set in order to predetermine an opening area of an opening part of the proportional solenoid control valves 15, 16, and an exciting current of level serving as the target value is carried without a time delay, in the case that the target value is smaller than the command value, to carry the exciting current of level serving as the target value with a certain time delay reversely in the case that the target value is larger than the command value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift truck cargo handling control device which facilitates alignment and improves workability by improving responsiveness at low speeds.

[0002]

2. Description of the Related Art A conventional cargo handling control device for a forklift truck has a structure in which a proportional electromagnetic control valve is energized with a time delay from the viewpoint of preventing accidents such as load collapse.

[0003]

As described above, since the proportional solenoid control valve is energized with a time delay, a time delay occurs even in a fine speed range, and when working at low speeds such as positioning. However, there was a problem that the response was slow, alignment was difficult, and workability was poor.

[0004]

SUMMARY OF THE INVENTION In a forklift truck having a proportional solenoid control valve for controlling a cargo handling work device by operating a cargo handling lever provided on a vehicle body, an exciting current flowing through the proportional solenoid control valve is provided. The target value of is set by the operation angle of the cargo handling operation lever, and the set target value is compared with the command value set to predetermine the opening area of the opening of the proportional solenoid control valve. If it is smaller than the value, energizing current of the magnitude that is the target value is applied without delaying time.On the contrary, if the target value is larger than the command value, the target value is delayed with a certain time. The present invention has been devised in order to solve the above problems as a configuration including a control device that supplies an exciting current of a certain magnitude.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a forklift embodying the present invention.
In particular, in a side view showing a counterbalance type, a counterbalance type forklift 1 has a vehicle body 2, steering wheels 3 arranged in front of the vehicle body 2, and drive wheels 4 arranged in the rear side thereof.
A mast 5 is erected in front of.

The mast 4 is composed of an outer mast 5A and an inner mast 5B. A lift bracket 6 which can move up and down is engaged with the inner mast 5B, and a fork 7 is attached to the lift bracket 6.

As shown in FIG. 2, the hydraulic circuit includes a tank 12 for storing hydraulic oil, a pump 13 for applying pressure to the hydraulic oil in the tank 12 and pumping the hydraulic oil to the outside, and a hydraulic motor for rotationally driving the pump 13. Hydraulic fluid discharged from the pump 13 and the proportional electromagnetic control valves 15 and 16 and the pipeline 1
It is supplied to the lift cylinder 10 and the tilt cylinder 11 which are connected by 7, 18 and the lift cylinder 10 moves the fork 7 up and down, or the tilt cylinder 11 is connected.
Generates a driving force that tilts the forks 7 in the vertical direction.

As shown in FIG. 3, a cargo handling operation lever 8, which is referred to as a lift operation lever 8 in this example, is arranged on the vehicle body 2, and a tilt angle is adjusted by a volume 9 fixed near the lift operation lever 8. To detect.

As shown in FIG. 4, the control device 20 comprises a CPU 21, a recording device 22 and an input / output device 23. The signal detected by the volume 9 is applied to the CPU 21 via the input / output device 23. The CPU 21
Then, the set value stored in the storage device 22 is collated with the above signal value, the set signal corresponding to the set value corresponding to the result of this collation is called, and the called set signal, that is, the target value and the proportional electromagnetic control. The opening area of the valve opening is compared with a command value set in the storage device 22 in advance, and if the target value is smaller than the command value, the target value is set to be the target value without a time delay. When the target value is larger than the command value, on the contrary, an output signal from the input / output device 23 is controlled to supply an exciting current of a magnitude that reaches the target value with a certain time delay. Emit.

The proportional solenoid control valve 1 based on the setting signal
The magnitudes of the currents flowing to the excitation coils 15A and 15B of Nos. 5 and 16 and whether or not to provide a delay time are controlled.

The control content of the control device 20 is such that the target value of the exciting current flowing through the proportional solenoid control valves 15 and 16 is set by the operation angle of the lift operating lever 8, and the set target value and the proportional solenoid control valve are set. The opening areas of the openings of 15 and 16 are compared with a command value set so as to be predetermined, and when the target value is smaller than the command value, the excitation of a size that is the target value without taking a time delay. On the contrary, when the target value is larger than the command value, an exciting current of a magnitude that reaches the target value is supplied with a certain time delay.

[0012]

As described above, according to the present invention, the target value of the exciting current flowing through the electromagnetic control valves 15 and 16 is set by the operation angle of the lift operating lever 8, and the set target value and the proportional electromagnetic are set. The opening areas of the control valves 15 and 16 are compared with a command value that is set in advance, and if the target value is smaller than the command value, the size that becomes the target value without a time delay is obtained. When the target value is larger than the command value, on the other hand, by supplying an exciting current of a magnitude that reaches the target value with a certain time delay to control, the response at low speed This makes it easier to perform various operations such as positioning, and can improve the efficiency of cargo handling work.

[Brief description of drawings]

FIG. 1 is a side view showing a forklift embodying the present invention, in particular, a counter balance type.

FIG. 2 shows a hydraulic circuit diagram.

FIG. 3 shows a configuration diagram of a cargo handling operation lever.

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

[Explanation of symbols]

 1 Counterbalance type forklift 2 Car body 3 Steering wheel 4 Drive wheel 5 Mast 6 Lift bracket 7 Fork 8 Cargo handling lever 9 Volume 15 Proportional electromagnetic control valve 16 Proportional electromagnetic control valve 20 Control device 21 CPU 22 Storage device 23 Input / output device

Claims (1)

[Claims] 1. A forklift truck having a proportional solenoid control valve for controlling a cargo handling device by operating a cargo handling lever provided on a vehicle body, wherein a target value of an exciting current communicating with the proportional solenoid control valve is set to a target value of the cargo handling lever. Set by the operation angle, compare the set target value and the command value set to preset the opening area of the opening of the proportional solenoid control valve, if the target value is smaller than the command value, Energize the exciting current of the target value without time delay, and if the target value is larger than the command value, apply the exciting current of the target value with a certain time delay. Forklift truck cargo handling control device including a control device for controlling the forklift truck.