JPH0419160B2 - - 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, it relates to a control method for controlling a control valve such as a cargo handling cylinder of a vehicle such as a forklift. Concerning a control method to achieve this.

(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 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 oil chamber 8, and the pilot piston 9 is connected to the spool of the control valve 2. It is connected to 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 rising 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, as shown in FIG. 2, a safety switch 19 is additionally connected to the controller 18 of the hydraulic circuit. A control valve control method for cargo handling, such as forklifts, has been 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 cargo handling control valve control method for a forklift, etc., when operating the cargo handling operation lever 17, the safety switch 1 is always activated.
The problem was that cargo handling operations were inconvenient and difficult because the operator had to press 9.

Therefore, in the present invention, if the operator presses the safety switch 19 even momentarily with a positive intention to operate, the vehicle can be loaded without losing safety even if the operator does not press the safety switch 19 continuously. The technical problem to be solved is to enable operation.

(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,
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, the cargo handling operation means is operated before the operation signal of the safety switch is turned on, and the operation signal of the safety switch is turned on during operation of the cargo handling operation means. In this case, a low-level control signal is initially output to the on-off valve, and the output level of the control signal is gradually increased to a level corresponding to the mid-operation of the cargo handling operation means. 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.

Furthermore, the operator operated the cargo handling operation means before operating the safety switch, and the operator operated the safety switch during the operation of the cargo handling operation means, so that an operation signal was output from the safety switch. In this case, the control device first outputs a control signal at a low output level to the on-off valve, and then gradually increases the output level of the control signal to a level corresponding to the operation level during the operation of the cargo handling operation means. The hydraulic actuator can be smoothly controlled by raising the pressure to .

(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, and the voltage signal output from the operating lever 17 is transmitted to an A/D converter 31. 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 soft start function is activated as shown in step S4.
When the tilt of the cargo handling operation lever 17 is operated beyond the neutral range, the CPU 33 gradually increases the output level from a low level without suddenly outputting the electromagnetic on-off valve drive signal corresponding to this operation angle. After setting the function
The process advances to step S5, while if the determination result in step S3 is YES, the process directly advances to step S5.

In step S5, the CPU 33 sets the state of the internal memory to an on state, that is, a state that remembers 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 S6, the CPU 33 determines whether the state of the internal memory is on or not, and if the determination result is NO, the process returns to step S2, while
If YES, it is determined in step S7 whether the inclination of the cargo handling operation lever 17 is within the range of the neutral width.

If the judgment result in step S7 is NO, step
In S8, the CPU 33 sets the state of the internal memory to the on state as in step S5, and also resets the timer as described above. In the next step S9, it is determined whether the soft start function is on. If the judgment result in step S9 is NO, in step S10 the CPU
33 outputs a control signal according to the inclination of the cargo handling operation lever 17 to the solenoid valve 1 via the interface 37.
4A drive circuit 38 or the solenoid valve 14B drive circuit 39;
9 to electromagnetic on-off valve 14A or electromagnetic on-off valve 14
A drive current corresponding to the inclination of the cargo handling operation lever 17 is applied to B, and then the process returns to step S7.

On the other hand, if the judgment result in step S9 is YES, the process moves to step S15, and in step S15, a constant current value α is set to the value of the drive current currently output to the electromagnetic on-off valve 14A or the electromagnetic on-off valve 14B. The added updated drive current value A is calculated.
In step S16, a drive current value A' of the electromagnetic on-off valve 14A or 14B corresponding to the current inclination of the cargo handling operation lever 17 is calculated. In the next step S17, the updated drive current value A
The magnitude of the drive current value A' corresponding to the current inclination of the cargo handling operation lever 17 is determined. step
If the determination result in S17 is A>A', the CPU 33 outputs a drive signal corresponding to the drive current value A' in step S18, turns off the soft start function in step S19, and then turns off the soft start function in step S19.
Return to S7. On the other hand, the judgment result in step S17 is A<
In the case of A', the CPU 33 outputs a drive signal corresponding to the drive current value A in step S20, and then
Return to step S7.

If the determination result in step S7 is YES, it is determined in step S11 whether or not the safety switch 19 is on. The judgment result of step S11 is
If YES, the process returns to step S5, while if the result of the determination in step S11 is NO, the count value of the timer is incremented by one in step S12, and the count value t is updated. step
In S13, it is determined whether the count value t of the timer has become equal to the time-up setting value T of the timer, and 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 S14. 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 S20, 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, and the safety switch 19 is operated during the operation of the cargo handling operation lever 17, the operation level of the cargo handling operation lever 17 during the above operation is changed. By gradually increasing the output level to the electromagnetic on-off valves 14A and 14B to the level of the corresponding control signal, the cargo handling operation is made safe and smooth.

In the above embodiment, a forklift was used as an example of the type of vehicle, but the present invention can also be applied to other industrial vehicles or agricultural vehicles equipped with a cargo handling device. Further, the electromagnetic on-off valve 14A,
14B may be replaced with an on-off valve other than an electromagnetic type.

(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.). If the cargo handling operation means is not operated even if the cargo handling operation means is operated, but once the safety switch is pressed, the cargo handling operation means becomes inoperable and if the cargo handling operation means is operated again within a certain period of time. The method enables cargo handling operation without pressing the safety switch again, and if the cargo handling operation means is operated before the safety switch is pressed and the safety switch is pressed during the operation, a rapid Since the cargo handling operation is controlled so as not to be performed, the cargo handling operation of the vehicle can be carried out safely and easily.

[Brief explanation of drawings]

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 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 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 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 is performed. Control is performed so that the operation signal from the safety switch is continuously output when the operation 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 to the on-off valve, furthermore, the cargo handling operation means is operated before the operation signal of the safety switch is turned on, and the safety switch is operated during the operation of the cargo handling operation means. When the signal is turned on, a low-level control signal is first output to the on-off valve, and the output level of the control signal is gradually raised to a level corresponding to the mid-operation of the cargo handling operation means. A method for controlling a remote control valve for cargo handling in a controlled vehicle.