JPH0422840B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a control method for controlling a control valve of a cargo handling cylinder, such as a lift cylinder or a tail cylinder, of a vehicle such as a forklift. This invention relates to a control method for safe cargo handling operations.

(Prior Art) Conventionally, an example of controlling a control valve for driving, for example, a lift cylinder of a forklift is disclosed in Japanese Utility Model Application Publication No. 107405/1983.

According to the same publication, as shown in the overall system diagram of FIG. Through the valve 5, the water is divided into a main pipe line 6 on the control valve 2 side and a PS pipe line 7 for power steering. An oil chamber 8 for pilot operation is formed on one side of the control valve 2.
A pilot piston 9 is slidably fitted into the control valve 2, and the pilot piston 9 is connected to a spool 10 of the control valve 2.
Note that the spool 10 is always held at a neutral position by a spring 11.

A pilot inflow pipe 12 introduces pilot pressure oil into both sides of the oil chamber 8 with the pilot piston 9 in between, and is connected to introduce the hydraulic pressure from the PS pipe 7. Pilot inflow pipe 1
A pressure reducing valve 13 is installed in the middle of the pipe 2 to protect the downstream part and stabilize the pilot oil pressure, and a normally closed electromagnetic on-off valve for ascending and descending is provided downstream from the branch point of the pilot inflow pipe 12. 14A and 14B are provided. Reference numeral 15 denotes a tank or a return pipe or a pilot drain pipe for leading out the pilot pressure oil in the oil chamber 8, and it communicates with both sides of the oil chamber 8 with the pilot piston 9 in between, and each has a throttle valve (orifice). It has 16.

17 is a cargo handling lever for remote control installed near the driver's seat, and 18
1 is a controller for driving and controlling the electromagnetic on-off valves 14A and 14B, which constitutes a valve control device. The cargo handling operation lever 17 has a tilting direction (operation direction) of the lever,
Outputs the signal of the tilt angle, while controller 1
8 applies a drive current according to the above signal to the electromagnetic on-off valve 1.
An electric circuit is formed to supply electricity to 4A or 14B.

Therefore, in the neutral state shown in the figure, when the lever of the cargo handling operation lever 17 is operated to tilt, for example, to the upward side, a signal indicating the tilting direction and the tilt angle is output, and upon receiving the signal, the controller 18 moves the lever to the upward side (corresponding to the tilting direction). In order to supply a drive current to the electromagnetic on-off valve 14A (on the right side in the figure) according to the inclination angle, the electromagnetic on-off valve 14A is activated. As a result, a controlled flow rate of pilot pressure oil flows into the oil chamber 8, and since its outlet side is restricted by the throttle valve 16, pressure is generated, and the spool 10 flows through the pilot piston 9. Switched to the rising side. At this time, the spool 10 is connected to the pilot pressure generated in the oil chamber 8 and the spring 11 that resists the pilot pressure.
Therefore, the position of the spool 10 can be adjusted by adjusting the operating amount of the electromagnetic on-off valve 14A, that is, the flow rate of the pilot pressure oil flowing into the oil chamber 8. can be controlled. That is, the rising speed of the lift cylinder 1 is appropriately controlled by changing the inclination angle of the cargo handling operation lever 17. It should be noted that it is operated in the same way when operating on the descending side.

(Problems to be Solved by the Invention) According to the above-mentioned conventional cargo handling control valve control method for controlling a lift cylinder such as a forklift or a tail cylinder, an operator does not have the intention to operate the cargo handling operation lever. There was a problem that it was dangerous because the cargo handling operation was carried out suddenly if it was tilted or the operator's elbow hit the cargo handling control lever.

Therefore, in the present invention, since the operation acceleration of the cargo handling operation lever, that is, the tilting acceleration, is generally large when the operation is not based on the operator's intention as described above, if the operation acceleration of the cargo handling operation lever is larger than the allowable value, The technical problem to be solved is to determine that the tilting motion is not based on the operator's intention, and to prohibit the supply of control current to the on-off valve.

(Means for solving the problem) The technical means for solving the above problem is to install a pilot pressure oil pipe line that introduces pilot pressure oil into the spool of a control valve that controls a hydraulic actuator, and a corresponding pilot pressure oil pipe line. With two pilot drain pipes for deriving pilot pressure oil,
A method for controlling a cargo handling control valve for a vehicle, in which one or both of the valves is provided with an on-off valve that is opened and closed by a control current supplied from a control device based on an operation signal corresponding to the amount of operation of a cargo handling operation lever, When the operation signal is output from the cargo handling operation lever, the operation acceleration of the cargo handling operation lever is calculated, and if it is determined that the operation acceleration exceeds a preset tolerance value, the control current is not energized to the opening/closing valve. It means to control by prohibiting it.

(Function) According to the above vehicle cargo handling control valve control method, when the cargo handling control lever is tilted by an operator or the like inadvertently touching the cargo handling control lever, the signal output from the cargo handling control lever, or When an operator or the like operates the cargo handling control lever with the intention of operating the cargo handling control lever, an operation signal outputted from the cargo handling control lever is inputted to the control device. When the above signal is input, the control device calculates the operating acceleration of the cargo handling operation lever based on the level change per unit time of the signal, and if the operating acceleration exceeds a preset tolerance value, the operator It is determined that the tilting movement of the cargo handling operation lever is not based on the user's intention to operate the cargo handling control valve, and the application of control current to the opening/closing valve for supplying hydraulic oil to the cargo handling control valve is prohibited. If the value is not exceeded, it is determined that the operator is carrying out the cargo handling operation with the intention of operation, and a control current is applied to the opening/closing valve based on the operation signal to control the cargo handling control valve. .

(Example) Next, an example of the present invention will be described with reference to the drawings.

In this embodiment, the control target is a hydraulic circuit having the same configuration as the hydraulic circuit for controlling the control valve that drives the lift cylinder 1 of the conventional forklift shown in FIG. The control valve control method for this purpose is shown below. Therefore, the reference numerals of the components used in this embodiment are the same as those shown in FIG.

FIG. 1 is an electrical control system diagram of this embodiment. As shown in the figure, the controller 18 is connected to an operating lever 17 that outputs a voltage signal corresponding to an operating inclination angle and an operating direction, that is, a lifting operation and a lowering operation.
The voltage signal output from 7 is sent to A/D converter 3.
1 is input. The A/D converter 31 is provided to convert the voltage signal into a digital signal, and the digital signal output from the A/D converter 31 is sent to a CPU (central processing unit) constituting a microcomputer via an input interface 32. 33. The CPU 33 has a random access memory RAM 34 and a read-on memory.
The ROM 35 and the clock 36 are connected, and the read-on memory ROM 35 includes electromagnetic on-off valves 14A and 1 that supply pressure oil to the control valve 2.
A control program for controlling the 4B and the like is stored.

An output interface 37 is connected to the output side of the CPU 33, and the control signal output from the CPU 33 is output to the drive circuit 38 for the solenoid valve 14A and the drive circuit 39 for the solenoid valve 14B via the output interface 37. Ru. The drive circuit 38 for the solenoid valve 14A and the drive circuit 39 for the solenoid valve 14B are connected to the solenoid on-off valves 14A and 14B, respectively, and the CPU 33 is connected to the solenoid on-off valves 14A and 14B.
A drive current corresponding to the control signal output from the controller is applied.

Next, the operation of this embodiment will be explained according to the flowchart shown in FIG.

When a power switch (not shown) is turned on and power is supplied to the controller 18, the CPU 33
Initializes internal registers, input/output sections, etc. as shown in step S1. In step S2, the CPU 33 inputs an A/D converted signal from the cargo handling operation lever 17 at predetermined intervals, for example, every 20 milliseconds, and determines whether the operation of the cargo handling operation lever 17 is based on the operator's will. , or no, a subroutine is started for applying control current to the electromagnetic on-off valves 14A and 14B or prohibiting the energization. In step S3, the operation signal input last time is compared with the operation signal input this time, and if it is determined that the voltage of the operation signal input this time is higher than the voltage of the operation signal input last time, the voltage of the operation signal input this time is determined to be higher than the voltage of the operation signal input last time. The voltage of the previously input operation signal is subtracted from the voltage of the input operation signal to find the potential difference A.

On the other hand, if the result of the judgment in step S3 is that the voltage of the operation signal input this time is lower than the voltage of the operation signal input last time, the voltage input this time is subtracted from the voltage of the operation signal input last time in step S5. Then, find the potential difference A. In step S6, step S4 or step S
The potential difference A obtained in step 5 is compared with a preset value α.

In step S6, if it is determined that the potential difference A is smaller than the set value α, that is, the cargo handling operation lever 1
7 is smaller than the preset value, in step S7 the electromagnetic on-off valves 14A,
Or, for the solenoid on-off valve 14B, the solenoid valve 14
An energization command signal for energizing the control current is output from the A drive circuit 38 or the solenoid valve 14B drive circuit 39. On the other hand, if it is determined in step S6 that the potential difference A is larger than the set value α,
That is, if the operation acceleration of the cargo handling operation lever 17 is larger than a preset value, it is determined that the tilting operation is not based on the operator's intention, and the control current for the electromagnetic on-off valve 14A or the electromagnetic on-off valve 14B is changed in step S8. After outputting an energization prohibition command signal for prohibiting energization, the process returns to the main routine (not shown). As shown in step S9, when it is determined that 20 milliseconds have elapsed in the main routine, the process returns to step S2 and steps S2 to S9 are executed.
Repeat the process.

As described above, when the operation signal from the cargo handling operation lever 17 is input and the degree of change in the operation signal per unit time, that is, the operation acceleration is larger than the allowable value,
It is determined that the cargo handling operation lever 17 has been tilted without the operator's intention, and control is performed to prohibit the control current from flowing to the electromagnetic on-off valve 14A or the electromagnetic on-off valve 14B, and the forklift cargo handling operation is performed. It is intended to make it safe.

(Effects of the Invention) As described above, according to the present invention, when the tilting acceleration of the cargo handling operation lever calculated based on the operation signal output from the cargo handling operation lever of the vehicle is larger than the allowable value, the operator It is possible to determine that the tilting movement of the cargo handling control lever is not based on the operator's intention, and to prohibit the supply of control current to the on-off valve that supplies pressurized oil to the cargo handling control valve, thereby preventing careless operation by the operator. When the cargo handling operation lever is tilted due to cargo handling operation or a similar action, the hydraulic actuator is not operated, thereby making cargo handling work safer.

[Brief explanation of drawings]

Fig. 1 is an electrical control block diagram used in one embodiment of the present invention, Fig. 2 is a hydraulic circuit diagram for driving a lift cylinder of a forklift, etc., and Fig. 3 is a flow chart showing the operation of this embodiment. be. DESCRIPTION OF SYMBOLS 1... Lift cylinder, 2... Control valve, 14A, 14B... Solenoid on-off valve, 17... Cargo handling operation lever, 18... Controller, S1-S9... Flowchart step.

Claims (1)

[Scope of Claims] 1. A pilot pressure oil pipe line for introducing pilot pressure oil into the spool of a control valve that controls a hydraulic actuator, and two corresponding pilot drain pipe lines for leading out the pilot pressure oil. control valve for cargo handling of a vehicle, which is equipped with an on-off valve that is opened and closed by a control current supplied from a control device based on an operation signal corresponding to the amount of operation of the cargo handling operation lever on one or both of the control valves. In the method, when the operation signal is output from the cargo handling operation lever, the operation acceleration of the cargo handling operation lever is calculated, and if it is determined that the operation acceleration exceeds a preset allowable value, a control signal is applied to the opening/closing valve. A control valve control method for vehicle cargo handling that prohibits the energization of control current.