JPH0641996Y2 - Lifting control device for cargo handling vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a lift control device for a cargo handling device in a cargo handling vehicle such as a forklift.

<Prior Art> Conventionally, an automatic lifting control device for a cargo handling vehicle has been disclosed in Japanese Patent Application No. 62-84.
As disclosed in No. 355 and No. 62-84356, a lift detector that continuously detects the lift of an attachment of a cargo handling vehicle and the detected lift of the lift detector until the required target lift is reached. Elevating control means for automatically raising or lowering the attachment and stopping it is provided.

In this automatic lift control system, the lift confirmation detector that detects that the attachment has reached the predetermined lift confirmation position and the lift confirmation detector when the lift confirmation position is detected by the lift confirmation detector. The lift detected by the high detector,
It is known to provide a means for comparing the lift with the lift confirmation position and stopping the automatic lift control when the deviation between the two exceeds a predetermined allowable value.

<Problems to be Solved by the Invention> However, in the conventional device, a microcomputer is used as a control device, which causes a problem that the cost is high and the operation is complicated and cumbersome.

In view of the above, an object of the present invention is to provide a lifting control device for a cargo handling vehicle that can smoothly lift and lower a load by a simple operation by using an inexpensive device.

<Means for Solving the Problem> The problem solving means according to claim 1 is, as shown in FIGS. 1 and 2, a fluid pressure circuit for raising and lowering the cargo handling apparatus 1, and a stop position when the cargo handling apparatus 1 is raised and lowered. Position detection switch 3, which detects
4, the approach detection switches 5 and 6 arranged on the front side of the position detection switches 3 and 4, and the output signals from the position detection switches 3 and 4 and the approach detection switches 5 and 6 to smoothly stop the cargo handling device 1. The control unit 7 includes a control unit 7 for stopping at a position, the control unit 7 switching the flow direction of the fluid pressure circuit 2, an operating lever 9 for switching the main valve 8, and an operating lever 9 Regardless of the operation, the release means 10 for switching the main valve 8 to the cargo handling device stop position by the output signals from the position detection switches 3 and 4, and the flow rate control for controlling the flow rate of the fluid pressure circuit 2 and smoothly operating the cargo handling device 1. The valve 11 and the electromagnetic switching valve 12 that controls the pilot pressure of the flow control valve 11 by the ON signals of the approach detection switches 5 and 6 are used.

In claim 2, as shown in FIG. 3, a fluid pressure circuit 2 for raising and lowering the cargo handling device 1, position detection switches 3 and 4 for detecting a stop position of the cargo handling device 1 when the cargo handling device 1 is raised and lowered, and the positions thereof. Control for smoothly stopping the cargo handling device 1 at the stop position by the output signals from the approach detection switches 5 and 6 arranged on the front side of the detection switches 3 and 4 and the position detection switches 3 and 4 and the approach detection switches 5 and 6. The control section 7 includes a section 7 and a main valve 8 for switching the flow direction of the fluid pressure circuit 2 by pilot pressure and a switching for switching the main valve 8 by supplying pilot pressure to the main valve 8 by operating an operating lever 9. The pilot pressure of the main valve 8 is controlled by the release signal 10 for switching the switching valve 28 to the cargo handling device stop position by the output signal from the valve 28 and the position detection switches 3 and 4, and the ON signal of the approach detection switches 5 and 6. Electromagnetic switching valve 12 that
It is composed of a and 12b.

<Operation> In the above problem solving means, in the claim 1, the cargo handling apparatus 1
To raise the main valve 8 with the operating lever 9.
Is switched to and held at the raised position, pressure oil is supplied to the fluid pressure circuit 2, and the cargo handling device 1 is raised.

When the cargo handling device 1 moves up and approaches a predetermined position, the upper approach detection switch 5 operates and outputs a signal. The flow control valve 11 is operated by the control unit 7, and the cargo handling device 1
The flow rate to is reduced.

At this time, the hydraulic pressure supply gradually decreases, and the rising speed of the cargo handling device 1 slows down. Then, when it moves up to a predetermined position, the upper position detection switch 3 operates and outputs a signal. Then, the release means 10 of the control unit 7 returns the main valve 8 to the neutral position, and the cargo handling apparatus 1 slowly stops.

Similarly, when the cargo handling apparatus 1 is lowered, the pressure oil from the cargo handling apparatus 1 is gradually discharged, so that the cargo handling apparatus 1 smoothly stops at a predetermined position.

In the second aspect, when raising the cargo handling apparatus 1, the switching valve 28 is switched to the raised position by the operation lever 9, and the pilot valve pressure switches and holds the main valve 8 to the raised position. Then, pressure oil is supplied to the fluid pressure circuit 2 to raise the cargo handling device 1.

When the cargo handling device 1 moves up and approaches a predetermined position, the upper approach detection switch 5 operates and outputs a signal. The electromagnetic switching valve 12a is actuated by the control unit 7 and the main valve 8
Pilot pressure to is reduced.

At this time, the operating speed of the main valve 8 gradually decreases,
The rising speed of the cargo handling device 1 becomes slower. Then, when it moves up to a predetermined position, the upper position detection switch 3 operates and outputs a signal. Then, the switching means 28 is returned to the neutral position by the releasing means 10, the supply of the pilot pressure to the main valve 8 is stopped, the main valve 8 is returned to the neutral position, and the cargo handling apparatus 1 is stopped gently.

Similarly, when lowering the cargo handling apparatus 1, the operating speed of the main valve 8 is gradually decreased, so that the cargo handling apparatus 1 smoothly stops at a predetermined position.

<Embodiment> An embodiment of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a circuit diagram of a lift controller showing a first embodiment of the present invention, and FIG. 2 is a side view of a forklift to which the lift controller of the present invention is applied.

As shown in the figure, the lift control device of the present embodiment includes a fluid pressure circuit 2 for raising and lowering a cargo handling device 1, position detection switches 3 and 4 for detecting a stop position of the cargo handling device 1 when moving up and down,
The cargo handling apparatus 1 is smoothly stopped at the stop position by the approach detection switches 5 and 6 arranged on the front side of the position detection switches 3 and 4 and the output signals from the position detection switches 3 and 4 and the approach detection switches 5 and 6. And a control unit 7 for
Is a main valve 8 for switching the flow direction of the fluid pressure circuit 2.
And an operating lever 9 for switching the main valve 8 and a release means 10 for switching the main valve 8 to the cargo handling device stop position by output signals from the position detection switches 3 and 4 regardless of the operation of the operating lever 9. And a flow rate control valve 11 for controlling the flow rate of the fluid pressure circuit 2 to smoothly operate the cargo handling apparatus 1, and an electromagnetic switching valve for controlling the pilot pressure of the flow rate control valve 11 by the ON signals of the approach detection switches 5 and 6.
It is composed of 12 and.

As shown in FIG. 2, the cargo handling apparatus 1 includes a mast 14 provided on the front surface of the vehicle body 13 and a fork 15 attached to the mast 14, and a lift cylinder for moving the fork 15 up and down in the mast 14. 16 are arranged.

The fluid pressure circuit 2 includes a lift cylinder 16, a pump 17, and a tank 18, which are connected via the main valve 8. The flow rate control valve 11 is provided between the main valve and the lift cylinder 16, and the check valve 19 is provided between the main valve 8 and the pump 17 to prevent the flow from the main valve 8 in the pump direction. Has been done.
Further, 20 is a relief valve.

The position detection switches 3 and 4 are mounted at predetermined height positions on the upper and lower parts of the mast 14, and the switches 3 and 4 are attached.
The proximity detection switches 5 and 6 close to the lower side and the upper side of
Is installed. As each switch, a limit switch, a proximity switch or the like is used. The position detection switches 3 and 4 and the approach detection switches 5 and 6 are connected to bipolar switches 21a, 22a, 21b and 22b for selecting a control position.

The main valve 8 is a three-position switching valve having five ports a to e. The main valve 8 is a port connected to the lift cylinder 16, a c port connected to a pump 17 via the check valve 19, a pump 17 and a tank. It has d port, e port and b port connected to 18.

Then, at the first position 8A of the main valve 8, the a port and the c port communicate with each other to raise the fork 15. Lift cylinder 16 is in communication with b port and d port at the second position 8B.
To stop. At the third position 8C, the a port and the e port communicate with each other, and the fork 15 is lowered.

Further, an operating lever 9 is attached to the outer end of the third position 8C, and an engagement for holding the switching position of the main valve 8 at the first position 8A or the third position 8C is attached to the outer end of the first position 8A. A piece 25 is attached, and an electromagnet 26 that engages with the engagement piece 25 is provided. Further, return springs 27a and 27b are provided at both ends.

The releasing means 10 is composed of the engaging piece 25, an electromagnet 26 and return springs 27a and 27b, and disengages the engaging piece 25 and the electromagnet 26 by the ON signal of the position detecting switches 3 and 4, and the main valve 8 To the second position 8B.

The flow rate control valve 11 is a two-position switching valve for fluid pressure drive, which connects the lift cylinder 16 and the pump 17 at the first position 11A and throttles the flow rate of the fluid pressure circuit 2 at the second position 11B. .

The electromagnetic switching valve 12 is a two-position switching valve, and the first position 12
The flow control valve 11 and the tank 18 communicate with each other at A, and the pump 17 and the flow control valve 11 communicate at the second position 12B. The approach detection switches 5 and 6 are connected to the electromagnetic switching valve 12 via the selection switches 21b and 22b, and when the switch is turned on, the electromagnetic switching valve 12 is switched to the second position 12B, and the flow control valve 11 is moved to the second position. Switch to 11B.

In the above configuration, when raising the cargo handling apparatus 1, the operation lever 9 is operated to switch the main valve 8 to the first position 8A. At this time, no power is supplied to the electromagnet 26 and the electromagnet 26 is in the expanded state, so that the electromagnet 26 is engaged with the engagement piece 25 to hold the main valve 8 at the first position 8A. Then, pressure oil is supplied from the pump 17 to the lift cylinder 16 to extend the lift cylinder 16 to raise the fork 15.

When the selection switches 21a and 21b are turned on and the fork 15 moves up to approach a predetermined position, the upper approach detection switch 5 is activated. Then, the electromagnetic switching valve 12
Is switched to the second position 12B, the flow rate control valve 11 is switched to the second position 11B by the pilot pressure, and the flow rate to the lift cylinder 16 is throttled.

At this time, the amount of hydraulic pressure supplied to the lift cylinder 16 gradually decreases, and the extension speed of the lift cylinder 16 decreases.
Then, when the fork 15 rises to a predetermined position, the upper position detection switch 3 operates and the electromagnet 26 is released. Then, the engagement with the engagement piece 20 is released, the main valve 8 returns to the neutral second position 8B by the spring 27a, and the cargo handling apparatus 1 slowly stops.

Similarly, when the cargo handling device 1 is lowered, if the selective switches 22a and 22b are turned on, the pressure oil from the lift cylinder 16 is gradually discharged, so that the cargo handling device 1 smoothly moves to a predetermined position. Stop.

Therefore, the lifting control device of the present invention is composed of inexpensive parts such as a switching valve and a proximity switch, and the cargo handling device 1 can be smoothly moved up and down to a predetermined position only by operating the operating lever.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a circuit diagram of a lift control device showing a second embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals.

In the lift control device of this embodiment, as shown in the drawing, the cargo handling device 1
Fluid pressure circuit 2 for elevating and lowering the cargo, and the cargo handling device 1
Position detection switch 3,4 that detects the stop position when moving up and down
And the approach detection switches 5 and 6 arranged on the front side of the position detection switches 3 and 4, and the output signals from the position detection switches 3 and 4 and the approach detection switches 5 and 6, so that the cargo handling device 1 can be smoothly stopped. The control unit 7 includes a main valve 8 for switching the flow direction of the fluid pressure circuit 2 by a pilot pressure and a main valve 8 for supplying the pilot pressure to the main valve 8 by operating an operating lever 9. 8 and switching means 28 for switching the switching valve 28 to the cargo handling device stop position by the output signals from the position detection switches 3 and 4, and the pilot signal of the main valve 8 by the ON signal of the proximity detection switches 5 and 6. It is composed of electromagnetic switching valves 12a and 12b for controlling pressure.

In the fluid pressure circuit 2, the main valve 8 and the lift cylinder 16 are directly connected to each other. The main valve 8 is a pilot control type switching valve, and its configuration is the same as that of the first embodiment.

The switching valve 28 comprises a raising switching valve 29 and a lowering switching valve 30, and the operating lever 9 attached to one end on the common side of the valves 29, 30 switches between raising and lowering. Further, at the other end, engaging pieces 31, 32 as releasing means 10 are provided.
Also, return springs 33 and 34 are attached, and electromagnets 35 and 36 that engage with the engagement pieces 31 and 32 are provided.

The f port and g port of the lowering switching valve 30 are
The lowering electromagnetic switching valve 12b and the main valve 8 are connected to the outer ends of the third position 8C, the h port is connected to the tank 18, and the i port is connected to the pump 17. In normal operation, the h port is in communication with the f and g ports, and in operation, the i port is in communication with the f and g ports.

The j-port and the k-port of the rising switching valve 29 are
The rising electromagnetic switching valve 12a and the main valve 8 are connected to the outer ends of the first position 8A, the 1 port is connected to the pump 17, and the m port is connected to the tank 18. The m port is in communication with the j and k ports during normal operation, and the l port is in communication with the j and k ports during operation.

The electromagnetic switching valves 12a and 12b are switched from a closed state to an open state by turning on the approach detection switches 5 and 6, and their outflow sides are connected to the tank 18, and throttles 37a and 37b are provided.

The position detection switches 3 and 4 are connected to the descending side electromagnet 36 and the ascending side electromagnet 35 via the selection switches 21a and 22a. The other structure is the same as that of the first embodiment.

In the above configuration, when raising the cargo handling apparatus 1, the operation lever 9 is operated to move the switching valve 28 to the lifting switching valve.
29, the electromagnet 35 is engaged with the engagement piece 31, and the switching valve 29 is kept in the operating state. Then, pressure oil is supplied from the pump 17, and the main valve 8 is driven by the pilot pressure.
Pressure is applied to the first position 8A side of to switch to the first position 8A.
Then, pressure oil is supplied from the pump 17 to the lift cylinder 16 to extend the lift cylinder 16 and raise the fork 15.

Fork 1 when selection switches 21a, 21b are on
When 5 moves up and approaches a predetermined position, the upper approach detection switch 5 operates. Then, the ascending electromagnetic switching valve 12a communicates with each other, and the pilot pressure of the switching valve 28 gradually decreases, and the spool of the main valve 8 slowly moves toward the neutral second position 8B. Along with that, the amount of hydraulic pressure supplied to the lift cylinder 16 gradually decreases,
The extension speed of the lift cylinder 16 becomes slower.

When the fork 15 rises to a predetermined position and the upper position detection switch 3 operates, the rising electromagnet 35 is released. Then, the engagement of the raising switching valve 29 with the engagement piece 31 is released, the switching valve 29 returns to the normal state, and the pressure oil to the pilot pressure is stopped.

When the pilot pressure is exhausted, the main valve 8 is held at the second position 8B, the pressure oil to the lift cylinder 16 is stopped, and the cargo handling apparatus 1 slowly stops.

Similarly, when the cargo handling device 1 is lowered, if the selection switches 22a and 22b are turned on, the cargo handling device 1 is smoothly stopped at a predetermined position by switching the main valve 8 slowly. You can

In this way, this embodiment can also achieve the same effects as the first embodiment.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, in the present invention, it is used for lifting control of the cargo handling device 1, but it may be applied to tilt control.

Alternatively, the stop position may be set in multiple stages by setting the position detection switch to an arbitrary position.

<Advantages of Device> As is apparent from the above description, according to the present invention, the cost is reduced as compared with the conventional device because the lift control device is composed of inexpensive parts such as a switching valve and an approach detection switch. In addition, there is an excellent effect that the cargo handling apparatus can be smoothly moved up and down to a predetermined position only by operating the operation lever.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a lift control device showing a first embodiment of the present invention, FIG. 2 is a side view of a forklift to which the lift control device of the present invention is applied, and FIG. 3 is a second view of the present invention. It is a circuit diagram of a lift control device showing an embodiment. 1: cargo handling device, 2: fluid pressure circuit, 3, 4: position detection switch, 5,
6: Approach detection switch, 7: Control part, 8: Main valve, 9: Operation lever, 10: Release means, 11: Flow control valve, 12: Electromagnetic switching valve.

Claims (2)

[Scope of utility model registration request] 1. A fluid pressure circuit for raising and lowering a cargo handling apparatus, a position detection switch for detecting a stop position of the cargo handling apparatus when moving up and down, and an approach detection switch arranged in front of the position detection switch. A main valve for switching the flow direction of the fluid pressure circuit and a main valve for switching the flow direction of the fluid pressure circuit, and a control section for smoothly stopping the cargo handling apparatus to the stop position by output signals from the position detection switch and the approach detection switch. An operation lever for switching operation, a release means for switching the main valve to the cargo handling device stop position by an output signal from the position detection switch regardless of the operation of the operation lever, and a smoothing of the cargo handling device by controlling the flow rate of the fluid pressure circuit. A flow control valve that is operated in the following manner, and an electromagnetic switching valve that controls the pilot pressure of the flow control valve by the ON signal of the proximity detection switch. Fork height control system for cargo handling vehicle, characterized in that it is configured. 2. A fluid pressure circuit for raising and lowering a cargo handling device, a position detection switch for detecting a stop position of the cargo handling device when moving up and down, and an approach detection switch arranged on the front side of the position detection switch. A control unit for smoothly stopping the cargo handling device to a stop position by output signals from the position detection switch and the approach detection switch, the control unit switching the flow direction of the fluid pressure circuit by pilot pressure, and an operation unit. A switching valve that supplies pilot pressure to the main valve by operating the lever to switch the main valve, a release means that switches the switching valve to the cargo handling device stop position by the output signal from the position detection switch, and an ON signal for the proximity detection switch. Lifting of a cargo handling vehicle, characterized by comprising an electromagnetic switching valve for controlling the pilot pressure of the valve. Control device.