JPH0451480B2 - - 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 such as a cargo handling cylinder of a vehicle such as a forklift, and more specifically, the present invention relates to a control method for controlling a control valve such as a cargo handling cylinder of a vehicle such as a forklift. This invention relates to a control method for facilitating control.

(Prior technology) Conventionally, as an example of control of a control valve that drives a lift cylinder of a forklift,
-There is one disclosed in Publication No. 107405.

According to the same publication, as shown in the overall system diagram of FIG. 5, the water is divided into a main pipe 6 on the control valve 2 side and a PS pipe 7 for power steering. An oil chamber 8 for pilot operation is formed on one side of the control valve 2, and a pilot piston 9 is slidably fitted into the oil chamber 8. It is connected to the spool 10.
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 pilot drain line for leading the pilot pressure oil in the oil chamber 8 to a tank or a return line, and it communicates with both sides of the oil chamber 8 with the pilot piston 9 in between, and is connected to 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, and these constitute a valve control device. The cargo handling operation lever 17 is operated in a tilting direction (operation direction) of the lever.
An electric circuit is formed so that the controller 18 outputs a signal indicating the inclination angle, and the controller 18 supplies a drive current corresponding to the above signal to the electromagnetic on-off valve 14A 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 lifting speed of the lift cylinder 1 is appropriately controlled by changing the inclination angle of the cargo handling operation lever 17. Note that it is operated in the same manner when operating to the descending side.

In the hydraulic circuit configured as described above, if the operator carelessly touches the cargo handling operation lever 17,
Since the lift cylinder 1 is activated, as a means to prevent the lift cylinder 1 from being activated due to this careless operation, a safety switch 19 is additionally connected to the controller 18 of the hydraulic circuit, as shown in FIG. A forklift cargo handling control valve control method is adopted in which the lift cylinder 1 cannot be operated by the cargo handling operation lever 17 unless the safety switch 19 is pressed.

(Problems to be Solved by the Invention) According to the conventional forklift cargo handling control valve control method described above, when operating the cargo handling operation lever 17, the safety switch 19 is always activated.
The problem was that loading and unloading operations were inconvenient and difficult because the operator had to push the button.

Therefore, in the present invention, the cargo handling operation lever 17
If the operator presses the safety switch 19 even momentarily with a firm intention to operate the forklift, the forklift can be used for cargo handling without losing safety even if the safety switch 19 is not pressed continuously. The technical problem to be solved is to facilitate operation.

(Means for solving the problem) Technical means for solving the above problem include a pilot pressure oil pipe that introduces pilot pressure oil into the spool of a control valve that controls a hydraulic actuator, and a corresponding pilot pressure oil pipe. With two pilot drain pipes for deriving pilot pressure oil,
Either or both of them are opened and closed by electrical signals output from the control device based on the operation signal corresponding to the operation of the cargo handling operation means and the operation signal of the automatic return type safety switch provided for safe operation. In a hydraulic control circuit for a cargo handling control valve of a vehicle equipped with an activated on-off valve, the control method for controlling the cargo handling control valve is such that the safety switch is instantaneously operated and the safety switch is operated from the same safety switch. When the signal changes from on to off in an instant, the operation signal is controlled so that it is continuously output for a certain period of time, and the control signal corresponding to the operation of the cargo handling operation means is outputted during this certain period of time. In addition to outputting to the on-off valve, if the operation signal of the safety switch is turned on and the operation signal from the safety switch is turned off while the cargo handling operation means is being operated, the cargo handling operation means is not operated. control so that the operation signal from the safety switch is output continuously for a certain period of time from the time when the cargo handling operation means is in a non-operating state, and corresponding to the operation of the cargo handling operation means. A control signal is output to the on-off valve, and further, when the cargo handling operation means is operated before the operation signal of the safety switch is turned on, the control signal is not output to the on-off valve. be.

(Function) According to the control valve control method for cargo handling in a vehicle, an operator operates the safety switch,
If the safety switch outputs an operation signal for a moment and then immediately turns off, the control device continues to control itself in the same state as if the operation signal had been output for a certain period of time, and When the cargo handling operation means is operated, a control signal corresponding to the operation of the cargo handling operation means is outputted to the opening/closing valve, and the cargo handling control valve is controlled to drive and control the hydraulic actuator.

Further, when the operator is operating the safety switch and the cargo handling operation means, the operator stops operating the safety switch in the middle of operating the cargo handling operation means, and the operation signal from the safety switch is not received. When turned off, the control device receives the operation signal from the safety switch when the cargo handling operation means is operated and for a certain period of time after the cargo handling operation means is in a non-operating state, for example, a neutral state. When the cargo handling operation means is being outputted continuously, the same state is maintained, and while the cargo handling operation means is being operated, a control signal corresponding to the operation of the operation means is output to the on-off valve, and the operation means is brought into a neutral state. Returning, the operation can be resumed again during the predetermined period of time, and the cargo handling control valve is controlled to drive and control the hydraulic actuator.

Further, if the operator operates the cargo handling operation means before operating the safety switch, the control device does not output a control signal to the on-off 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. , and a control valve control method for facilitating the control. Therefore, the explanation numbers used in the explanation of this embodiment are the same as the explanation numbers 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, that is, a cargo handling operating lever 17 that outputs a voltage signal corresponding to the operating inclination angle. is input. A/D converter 3
1 is provided for converting the above voltage signal into a digital signal, and the digital signal output from the A/D converter 31 is inputted to a CPU (central processing unit) 33 constituting a microcomputer via an input interface 32. Ru. Further, a safety switch 19 is connected to the input interface 32 of the controller 18. The CPU 33 has a random access memory RAM 34 and a read-only memory.
A ROM 35 and a clock 36 are connected, and the read-only memory ROM 35 has the electromagnetic on-off valve 1.
A control program for controlling 4A, 14B, etc. 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. A solenoid valve 14A drive circuit 38 and a solenoid valve 14B drive circuit 39 are connected to the solenoid valves 14A and 14B, respectively.

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 determines whether or not the safety switch 19 is turned on, and turns the safety switch 19 on.
When it is determined that the load handling operation lever 17 is turned on, in the next step S3, the operation level of the cargo handling operation lever 17, that is, the inclination of the lever 17 is set within a slight inclination angle range (neutral width) set in advance for safe operation. Determine whether or not. Note that even if the cargo handling operation lever 17 is tilted within the above neutral width range,
The range of the inclination angle is set so that the CPU 33 does not output a control signal for controlling the electromagnetic on-off valves 14A and 14B.

If the judgment result in step S3 is NO, the process returns to step S2, while if the judgment result in step S3 is YES, the process moves to step S4.

In step S4, the CPU 33 sets the state of the internal memory to an on state, that is, a state in which it is remembered that the safety switch 19 has been turned on, and further resets a timer for counting the on-memory time in the internal memory. (t=0).
In step S5, the CPU 33 determines whether the state of the internal memory is on or not. If the determination result is NO, the process returns to step S2, while
In the case of YES, it is determined in step S6 whether the inclination of the cargo handling operation lever 17 is within the range of the neutral width.

If the judgment result in step S6 is NO, step
In S7, the CPU 33 sets the state of the internal memory to the on state as in step S4, and also resets the timer as described above. In the next step S8, the CPU 33 controls the load handling operation lever 1.
A control signal corresponding to the inclination of 7 is outputted via the output interface 37 to the drive circuit 38 for the solenoid valve 14A or the drive circuit 39 for the solenoid valve 14B.
Alternatively, a drive current corresponding to the inclination of the cargo handling operation lever 17 is applied to the electromagnetic on-off valve 14B, and then the process returns to step S6.

If the determination result in step S6 is YES, it is determined in step S9 whether the safety switch 19 is on. The judgment result of step S9 is
If YES, the process returns to step S4, while if the result of the determination in step S9 is NO, the count value of the timer is incremented by one in step S10, and the count value t is updated. step
In step S11, it is determined whether the count value t of the timer has become equal to the time-up setting value T of the timer. If the determination result is YES, the state of the internal memory of the CPU 33, that is, the safety switch 19 is changed in step S12. It remembers that it was turned on and sets it to OFF, then the step
Return to S2.

As mentioned above, step S2 of the flowchart
By repeating ~S12, the safety switch 19
Even if is pressed momentarily, if the CPU 33 receives the output signal from the safety switch 19, the CPU
33 enables cargo handling operation using the cargo handling operation lever 17 for a certain period of time after the safety switch 19 becomes inoperable. In addition, the cargo handling operation lever 17
Even if the operation of the safety switch 19 is released during the operation, the CPU 33 enables the cargo handling operation until the cargo handling operation lever 17 returns to the neutral state, and once it returns to the neutral state, the CPU 33 allows the cargo handling operation to be performed for a certain period of time after returning to the neutral state. to enable the operation of the cargo handling operation lever 17 to be resumed. Furthermore, if the cargo handling operation lever 17 is operated before the safety switch 19 is operated, interlock control is performed so that the cargo handling operation is not performed.

In the above embodiment, a forklift was used as the type of vehicle, but the present invention can be applied to any vehicle other than a forklift as long as it is equipped with a control valve for cargo handling. Further, in place of the electromagnetic on-off valves 14A and 14B, on-off valves other than electromagnetic type may be used.

(Effects of the Invention) As described above, according to the present invention, when handling cargo using a vehicle such as a forklift, there is no need to continuously press the safety switch when operating the cargo handling operation means, and there is no need to continuously press the safety switch when operating the cargo handling operation means. This prevents the cargo handling operation from suddenly stopping even if you inadvertently stop operating the safety switch midway through, and also prevents the cargo handling operation from stopping suddenly after a certain period of time has passed since the cargo handling operation means is in a non-operational state (neutral state, etc.). Even if the cargo handling operation means is operated in a timely manner, the cargo handling operation is not activated, and if the cargo handling operation means is operated again within a certain period of time after the cargo handling operation means is in the inoperable state, the safety switch is pressed. In order to make it possible to carry out the cargo handling operation without any trouble, and to control the cargo handling operation so that the cargo handling operation is not carried out if the cargo handling operation means is operated before the safety switch is pressed, the forklift cargo handling operation can be carried out safely and
This has the effect of making it easier.

[Brief explanation of the drawing]

FIG. 1 is an electrical control system diagram of an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram, and FIG. 3 is a flow chart for explaining the operation. 1...Lift cylinder, 2...Control valve, 3...Hydraulic pump, 9...Pilot piston, 10...Spool, 14A, 14B...Solenoid on-off valve, 17...Operation lever, 18...Controller, 19 ...Safety switch, 33...CPU.

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. Electricity is output from a control signal to one or both of the control signals based on the operation signal corresponding to the operation of the cargo handling operation means and the operation signal of the automatic reset type safety switch provided for safe operation. A control method for controlling the cargo handling control valve in a hydraulic control circuit for a cargo handling control valve of a vehicle equipped with an on-off valve that is opened and closed by a signal, wherein the safety switch is instantaneously operated and the same When the operation signal from the safety switch changes from on to off instantaneously, the operation signal is controlled so as to be continuously output for a certain period of time, and the operation of the cargo handling operation means is performed during this certain period of time. outputs a control signal to the on-off valve, and when the operation signal of the safety switch is turned on and the operation signal from the safety switch is turned off while the cargo handling operation means is being operated, the cargo handling operation is performed. The cargo handling operation means is controlled so that the operation signal from the safety switch is continuously output when the means is being operated and for a certain period of time from when the cargo handling operation means is in a non-operating state. outputs a control signal corresponding to the operation of the on-off valve to the on-off valve, and furthermore, when the safety switch is operated after the cargo handling operation means is operated and the operation signal of the safety switch is turned on, the on-off valve is A method for controlling a control valve for cargo handling in a vehicle that controls not to output a control signal.