JPS6391523A - Load display apparatus - Google Patents

Abstract

PURPOSE:To eliminate the display unclearness of load, by displaying load when the variation in the pressure of a hydraulic circuit driving a cargo-handling apparatus in lifting a cargo by the cargo-handling apparatus. CONSTITUTION:A pressure sensor 1 detects the hydraulic pressure of a lift cylinder 2 by utilizing that the hydraulic pressure in the cylinder 2 is proportional to the load of the cargo W applied to a lift and output a hydraulic pressure detection signal to a controller 3. The hydraulic pressure detection signal is inputted to CPU 6 through an amplifier 4 and an A/D converter 5. When the variation of the hydraulic pressure detection signal becomes smaller than a preset value, CPU 6 displays load data on a display 11 on the basis of the hydraulic detection signal inputted at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) This invention relates to a load display device for an industrial vehicle.

(Prior art) In the case of industrial vehicles such as forklifts, if the weight σ of the load to be handled is heavier than the handling weight σ of the cargo handling equipment, there is a risk that the cargo handling equipment may fall over or the supporting parts of the cargo handling equipment may be damaged. A system has been proposed that displays carts being worked on. In conventional equipment that displays load during cargo handling operations, pressure fluctuations occur in the hydraulic circuit that drives the cargo handling device when the cargo is first lifted by the cargo handling device, so the load display on the load display device is unstable, and There was an issue where it was unclear whether the display was accurate.

In order to solve this problem, Japanese Patent Application Laid-Open No. 55-163301
No. is proposed. In this load display device, a damper device is built into the hydraulic circuit, which reduces fluctuations in the hydraulic pressure in the hydraulic circuit that occur when the cargo is lifted by a cargo handling device, and stabilizes the load display on the load display device.

(Problems to be Solved by the Invention) However, in the industrial vehicle proposed as described above, it is necessary to incorporate a damper device into the hydraulic circuit, and there is a problem that the hydraulic circuit becomes complicated.

The present invention has been made to solve the above-mentioned problems, and its object is to provide a load display device that can stably display a load without the need to incorporate a damper device into a hydraulic circuit.

Structure of the Invention (Means for Solving Problems) This invention includes a load detection means for detecting a load during cargo handling work, and a detection signal input from the load detection means from time to time, and a detection signal inputted at that time. a calculation means for calculating the difference between the signal and the previously input detection signal; a comparison means for comparing the calculation result of the calculation means with a predetermined set value;
As a result of the comparison, if the comparison means is larger than the set value, the load data based on the detection signal input at that time is not displayed, and when it is determined that the calculation result is smaller than the set value, the load data based on the detection signal input at that time is displayed. The gist thereof is to include a control means for outputting load data to an output device based on a signal.

(Operation) The calculation means inputs the detection signal from the load detection means at each time, and calculates the difference between the detection signal input at that time and the detection signal input last time. Then, the comparison means compares the calculation result of the calculation means with a predetermined set value. As a result of the comparison by the comparison means, when the calculation result is larger than the set value, the control means does not display the load display data based on the detected signal, and when it is determined that the calculation result is smaller than the set value. , outputs load data to the output device based on the detection signal input at that time.

(Example) Hereinafter, an example in which the present invention is embodied in a load display device for a forklift will be described with reference to FIGS. 1 and 2.

First, the electrical configuration of this load display device will be explained. A pressure sensor 1 as a load detection means is provided in a lift cylinder 2. The pressure sensor 1 detects the oil pressure in the lift cylinder 2 by utilizing the fact that the oil pressure in the lift cylinder 2 is proportional to the load of the load W applied to the lift, and outputs an oil pressure detection signal to the controller 3.

The controller 3 includes an amplifier 4 that amplifies the oil pressure detection signal to an appropriate size, and an A/D converter 5 that converts the amplified oil pressure detection signal from an analog value to a digital value.
A central processing unit (hereinafter referred to as CPU) 6 as arithmetic means, comparison means and control means, an interface 7 and a clock integrated circuit (hereinafter referred to as clock LSI)
It consists of 8. The CPU 6 has a clock L
The current oil pressure detection signal is read based on the SI reference pulse signal.

The CPU 6 stores various control programs such as an arithmetic control program and a display control program in a program memory 9 consisting of a read-only memory (ROM), and performs arithmetic processing based on this control program, as well as outputs the display 11, etc. Control and drive the device.Also, C
The PU 6 includes a working memory 10 consisting of a memory (RAM) that can be accessed and written to, and stores the results of the arithmetic processing performed at the time. The display 11, which is one of the output devices, is provided on the instrument panel of the driver's seat of the forklift, and is capable of displaying multiple digits, each digit consisting of a 7-segment LED.

Next, the operation of the load display device configured as described above will be explained with reference to FIG.

When the power is turned on and you start driving or cargo handling, C
The PU 6 initializes the contents of the working memory 10, various flags, etc. in step 1 (hereinafter step is represented by S).

Then, the CPU 6 reads the oil pressure detection signal from time to time, calculates the load of the load W loaded by the lift based on the oil pressure detection signal read at that time, and stores the load data in the first load data storage area of the working memory 10. The content of is rewritten to the calculation result (hereinafter referred to as load data D1), and the previous calculation result (hereinafter referred to as load data D2) that was previously stored in the first 'R heavy data storage area is 2 to the load data storage area. Further, the CPLI 6 calculates the difference 1dl between the load data D1 stored in the first load data storage area at that time and the load data D2 newly stored in the second load data storage area (S3).

Next, CPLJ6 uses the difference 1dl and the program memory 9.
1d.
l> When the set value δ, the determination in S4 is NO and the process returns to S2. On the other hand, when ldl≦set value δ, the CPU 6 makes a YES determination in S4, and displays the load in S5.

That is, the CPtJ6 reads the load data D1 stored in the first load data storage area, outputs it to the display 11 via the interface 7, and displays the load data D1.

Therefore, since the pressure fluctuation is large, when the difference 1 dl is 1 dl>set value δ, it is not displayed on the display 11,
When the pressure fluctuation becomes small and ldl≦setting value δ, C
The PU 6 displays load data based on the oil pressure detection signal on the display 11.

Note that the present invention is not limited to the above-mentioned embodiment, and the display 11 is provided with a notification lamp, and furthermore, in the flowchart, when ldl>set value δ,
It is also possible to make arbitrary changes within the scope of the spirit of the invention, such as providing a step of outputting a notification signal to notify that the pressure is fluctuating and lighting up a notification lamp while returning from 4 to 82. be.

Effects of the Invention As detailed above, this invention differs from conventional methods in that when a large pressure fluctuation occurs in the hydraulic circuit that drives the cargo handling device when a load is lifted by the cargo handling device, the load on the load display device is displayed. Since the load is displayed when the pressure fluctuation becomes small without being displayed, it is possible to see the load display after it has stabilized. Therefore, ambiguity in the load display can be eliminated, and there is no need to check the load display unlike in the past.

Also, since there is no need to install a damper device in the hydraulic circuit,
This has the remarkable effect that the hydraulic circuit does not become complicated.

[Brief explanation of the drawing]

FIG. 1 is an electrical block circuit diagram of an embodiment embodying the present invention, and FIG. 2 is a flowchart. 1 is a pressure sensor as a load detection means, 2 is a lift cylinder, 3 is a controller, 6 is a central processing unit (CPU) as a calculation means, comparison means and control means, 10 is a working memory as a storage means, 11 is a This is a display that serves as an output device.

Claims (1)

[Claims] A load detection means for detecting a load during cargo handling work, and a detection signal from the load detection means at each time is inputted, and a difference between the detection signal inputted at that time and the detection signal inputted last time. a calculation means for calculating the calculation result of the calculation means, a comparison means for comparing the calculation result of the calculation means with a predetermined set value, and a detection signal input at that time when the comparison result of the comparison means is larger than the set value. A load display device comprising: a control means that outputs load data to an output device based on a detection signal input at that time when it is determined that a calculation result is smaller than a set value without displaying load data based on the set value.