JPH08109000A - Lifting height regulating device for forklift - Google Patents

Abstract

PURPOSE: To surely conduct setting and release of lifting height regulation by using an oil pressure cylinder from an operator seat. CONSTITUTION: Respective lift, tilt, and shift cylinders 4, 8, 51 are connected to respective control valves 42-44 and operated by means of operation levers S1-S3. A stopper is turnably provided outside an outer mast and is positioned at a regulating position and a release position by means of an oil pressure cylinder 16, which is connected to the control valve 44. Solenoid valves 59, 60 are connected between the control valve 44 and respective cylinders 16, 51, and are also connected to a lifting height regulating switch 10. The switch 10 is connected to a power source 61 via a timer circuit 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lift control device for a forklift for controlling the upper limit of the lift of a forklift.

[0002]

2. Description of the Related Art Conventionally, when carrying a container using a forklift between a freight car parked on a railway lead-in line and an unloading station, work with the forklift passing under the railway overhead line. It is carried out. At this time, if the forklift lifts the container above a certain height, the inner mast or the upper part of the container cushions the overhead line of the railway. Therefore, in some cases, the forklift may damage the overhead line, which may hinder the operation of the railway. Therefore, in order to reliably prevent the forklift from interfering with the overhead line, a lifting height that prevents the fork from being lifted above a predetermined height when operating, loading and unloading the forklift under the overhead line. It is designed to activate the restraint system.

This lift control device is provided at a predetermined position outside the outer mast, and has a plurality of proximity switches for detecting a rising fork bracket, a lift restricting portion for restricting lift of the lift bracket, a hydraulic pump and a lift. It is composed of an unload valve for stopping the supply of hydraulic oil to the cylinder, a control unit for operating the unload valve based on a detection signal from each proximity switch, and the like.
The proximity switches are arranged at different heights of the outer mast, and detect the different heights of the lift bracket that rises.

A pair of rising restricting portions are provided at the same height outside the left and right outer masts. As shown in FIG.
The rising restricting portion includes a block-shaped stopper arm 74 and bearings 72, 73 that are vertically provided outside the outer mast 71.
Is rotatably supported by a pin 75. Positioning holes 72a. 72b
Is vertically penetrated. Then, when the lock bolt 76 is inserted into the positioning holes 72a and 72b in a state where the stopper arm 74 is rotated forward or backward of the outer mast 71, the stopper arm 74 is fixed so as not to be rotatable at that position. There is. In the state where the stopper arm 74 is rotated forward, the front end of the stopper arm 74 is arranged at the regulation position in which the front end of the outer mast 71 is projected forward. The lower surface of the front portion of the stopper arm 74 comes into contact with stoppers provided on the left and right sides below the lift bracket (not shown).

Further, in this state, the limit switch 78 arranged below the bearing 73 is turned on by the engaging rod 77 provided on the lower surface of the stopper arm 74. When the limit switch 78 is turned on, a control unit (not shown) similarly operates an unload valve (not shown) based on the signals from the proximity switches. Further, when the stopper arm 74 is rotated rearward, the stopper arm 74 is arranged at the release position which is retracted rearward from the front end of the outer mast 71. In this state, the engaging rod 77
Does not engage the limit switch 78, the limit switch 78 is turned off.

[0006] Each proximity switch has a left and right outer mast 7
The lift brackets arranged at different heights are detected by dogs provided at the right and left positions thereof. The stopper arm 74 is arranged at the regulation position,
When the lift bracket is raised with the limit switch 78 turned on, the dog is first detected by the regular proximity switch arranged at the lowest position. When the regular proximity switch is turned on in the state where the stopper arm 74 is arranged at the regulation position and the limit switch 78 is turned on, the unload valve is operated by the control unit. Then, since the supply of the hydraulic oil to the lift cylinder is stopped, the lift bracket is prevented from rising.

[0007] Normally, the lifting of the lift bracket is stopped by the operation of the service proximity switch. The lift bracket that has stopped moves down by operating the lift lever. A return limit switch is arranged below the regular proximity switch, and the lift bracket that has descended turns on the return limit switch. When the return limit switch is turned on, the operation of the unload valve is stopped and the hydraulic oil is supplied to the control valve again, so that the lift bracket can be raised again.

If the service proximity switch does not work normally for some reason and the unload valve does not work, the lift bracket does not stop at that position and continues to rise. As a result, the lift bracket is detected relative to the first emergency proximity switch which is located slightly higher than the normal proximity switch. When the first emergency proximity switch is turned on, the unload valve operates and the supply of hydraulic oil to the lift cylinder is stopped, so the lift bracket is stopped from rising. As a result, the lift bracket stops at a position slightly higher than the height at which it stops with the regular proximity switch.

Further, if the first emergency proximity switch does not operate normally for some reason and the unload valve does not operate, the lift bracket does not stop at that position and continues to rise. As a result, the lift bracket is detected relative to the second emergency proximity switch which is arranged at a position slightly higher than the first emergency proximity switch. When the second very close switch is turned on, the unload valve operates to stop the supply of hydraulic oil to the lift cylinder, so that the lift bracket is stopped from rising. As a result, the lift bracket stops at a position slightly higher than the height at which the lift bracket stops at the first emergency proximity switch.

Furthermore, if the second emergency proximity switch does not operate normally for some reason and the unload valve does not operate, the lift bracket does not stop at that position and continues to rise. As a result, the left and right stoppers on the lower side of the lift bracket come into contact with the lower surface of the stopper arm 74 that is disposed at the restricting position and protrudes forward of the outer mast 71, and the lifting of the lift bracket is mechanically stopped. When this happens, the driver immediately stops the fork raising operation. When the lift bracket is engaged with the stopper arm 74 and stopped, the upper end of the inner mast or the upper end of the container is arranged at a position sufficiently lower than the overhead wire.

As a result of the above, since the ascent of the fork is surely restricted to a predetermined elevation or less, it is possible to prevent the raised container or the inner mast from buffering the overhead wire.

[0012] When a worker loads a container on a freight car through an overhead line or unloads a container on a freight car,
After getting off from the driver's seat, the stopper arms 74 attached to the left and right outer masts 71 are rotated from the normal release position to the restricting position and fixed with the lock bolts 76. As a result, the limit switch 78 operates, and the control unit operates the unload valve based on the signals from the regular proximity switch, the first emergency proximity switch, and the second emergency proximity switch. The worker loads or unloads the container on the freight car while passing under the overhead wire in this state.

By the way, when a container unloaded from a freight car is to be placed at the loading place, the container is stacked and stored in order to reduce the occupied area of the container and to shorten the traveling distance of the forklift at the time of loading. To do. At this time, if the lifting control device remains in the operating state, the lift bracket cannot be sufficiently raised, and thus the containers cannot be stacked. Therefore, when the forklift enters the loading place, the driver descends from the driver's seat and changes the stopper arm 74 set at the regulation position to the release position. As a result, even if the limit switch 78 is turned off and each proximity switch is turned on, the unload valve is not operated, the stopper arm 54 is not engaged with the stopper of the lift bracket, and the lift restriction is released. Therefore, the forks can be raised to their maximum lift and containers can be stacked.

[0014]

However, the work of unloading a container from a freight car and placing it on the freight car must be carried out promptly in a situation where the freight car moves in and out of a lead-in line or the like. Therefore, setting and releasing the lifting control device from the driver's seat is a hindrance to quick work.

Therefore, a method has been proposed in which the stopper arm 74 is provided so that it can be driven by an electric cylinder or the like, and the electric cylinder is operated from the driver's cab, but power consumption for driving the electric cylinder or the like is extra. There is a problem.

The present invention has been made in order to solve the above problems, and its purpose is to lift and fork lift of a forklift truck which can surely set and release the lift control from a driver's seat by using a hydraulic cylinder. To provide a highly regulated device.

[0017]

In order to solve the above-mentioned problems, the invention according to claim 1 is a forklift in which a fork is attached to a lift bracket which can be raised and lowered along an outer mast, and the fork is raised and lowered together with the lift bracket. A fork operating means that is provided in the cab of the forklift and that operates to drive the fork, a fork hydraulic cylinder that drives the fork based on the operation of the fork operating means, and an operation of the fork operating means Control valve for controlling the hydraulic oil supplied from the hydraulic oil supply source to the hydraulic cylinder, a regulation position provided on the outer mast for stopping the fork by engaging the lift bracket, and the lift bracket are engaged. Can be positioned in two positions, a release position A control member, a control hydraulic cylinder for positioning the control member at the two positions based on an operation of the fork operating means, and a control valve provided in the driver's cab, to which hydraulic oil from a control valve is connected. Switching operation means for operating to supply either the fork or regulation hydraulic cylinder, and the operating oil is supplied to the fork or regulation hydraulic cylinder based on the operation of the switching operation means. The gist of the invention is to have a switching means.

According to a second aspect of the invention, in the first aspect of the invention, the switching means is an electromagnetic valve provided between the control valve and the fork hydraulic cylinder and between the control valve and the regulating hydraulic cylinder. Its main point is that it is a valve.

According to a third aspect of the invention, in the second aspect of the invention, a timer circuit is connected to the switching operation means, and the hydraulic oil is supplied to the regulating hydraulic cylinder based on the operation of the switching operation means. The point is that the timer circuit starts timing at the time of starting, and the solenoid valve is switched to supply hydraulic oil to the fork hydraulic cylinder after a predetermined time has elapsed based on the timing of the timer circuit.

[0020]

Therefore, according to the first aspect of the invention, the control valve supplies the hydraulic oil from the hydraulic oil supply source to the fork hydraulic cylinder based on the operation of the fork operating means, and the hydraulic cylinder is supplied. Fork drive is performed by expanding and contracting based on the hydraulic oil.

When the switching operation means is operated while the fork is being driven, the switching means supplies hydraulic oil to the restriction hydraulic cylinder based on the operation of the fork operation means, and the restriction hydraulic cylinder can be operated. Like Then, the fork operating means is operated to position the regulating member at the regulating position or the releasing position. When the fork rises when the restricting member is in the restricting position, the restricting member eventually contacts the lift bracket, and the lift bracket, that is, the fork stops at the contact position.

According to the second aspect of the present invention, the solenoid valve is operated based on the operation of the switching operation means, and the hydraulic oil from the control valve is supplied to either the fork driving or regulating hydraulic cylinder. .

According to the third aspect of the present invention, after the regulation hydraulic cylinder is operated by the fork operating means, the switching means is switched by the timer circuit after a predetermined time, and the fork operating means is operated by the fork operating means. Is operated.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. FIG. 1 shows a forklift 1 for loading and unloading a container C on a freight car while passing under an overhead wire K in a rail line.

As shown in FIGS. 1 and 2, the inner masts 3R and 3L are movably supported between the left and right outer masts 2R and 2L of the forklift 1, and are lifted and lowered by a lift cylinder 4 as a fork hydraulic cylinder. It is like this. A lift bracket 5 is supported between the inner masts 3R and 3L so as to be able to move up and down. Two forks 7 are attached to the front surface of the lift bracket 5 via a finger board 6. A backrest 6A is fixedly installed on the finger board 6. Various loads such as the container C are placed on the fork 7.
Also, the main body of the forklift 1 and the outer masts 2R, 2
It is connected to L via a tilt cylinder 8 as a fork hydraulic cylinder, and the fork 7 is tiltably provided by the tilt cylinder 8 together with the outer masts 2R and 2L. Further, both forks 7 are provided so as to be able to move (shift) left and right along the fingerboard 6. The shift of these forks 7 is performed by a shift cylinder 51 as a fork hydraulic cylinder described later. That is, in the forklift 1, ascending and descending, tilting and shifting of the fork 7 are performed as a fork drive.

In the cab 9 of the forklift 1,
Lift, tilt and shift operation levers S1 to S3 as fork operating means for operating the lift cylinder 4, tilt cylinder 8 and shift cylinder 51.
Is provided. Further, a lift control switch 10 as a switching operation means is provided in the cab 9.

As shown in FIGS. 3 and 4, the right outer mast 2R of the forklift 1 is provided with a bracket 11 having a U-shaped cross section at the outer upper portion thereof. The bracket 11 is arranged so that the front side is opened. A stopper 12 serving as a plate-shaped restricting member is disposed in the opening 11a of the bracket 11 which is opened. The stopper 12 has a pin 13 at the base end, and the bracket 11
Is pivotally supported on the pin 13 and is rotatable about the pin 13. A substantially L-shaped mounting plate 14 is provided on the stopper 12.
Is attached. Further, in the outer mast 2R, a mounting projection 15 is attached above the rear portion of the bracket 11. The hydraulic cylinder 16 is attached to the protrusion 15.
The base end of is attached rotatably. A U-shaped mounting plate 17 is attached to the tip of the piston rod 16a of the hydraulic cylinder 16. The mounting plate 17 is rotatably provided on the mounting plate 14 by a pin 18. The stopper 12 is rotated based on the expansion and contraction of the piston rod 16a of the hydraulic cylinder 16 serving as the restricting hydraulic cylinder. That is, the piston rod 16
When a is extended, the front end portion of the stopper 12 is arranged at a position (regulating position) protruding from the front side of the outer mast 2R. Further, when the piston rod 16a is in a contracted state, the front end portion of the stopper 12 does not project from the front side of the outer mast 2R and is substantially perpendicular to the outer surface of the outer mast 2R, as shown by the imaginary line in FIG. (Release position)
Is installed in.

Further, a bar 9 is attached to the stopper 12 at a position in front of its base end. A limit switch 20 is attached to the lower side of the bracket 11. That is, the limit switch 20 is turned on when the bar 19 pushes the detecting portion 20a when the stopper 12 is in the releasing position.

The bracket 11, the stopper 12, the hydraulic cylinder 16, the limit switch 20 and the like constitute an ascending regulation portion 21. As shown in FIGS. 2 and 3, on the outer side of the right outer mast 2R, a return limit switch 22 is fixed to the upper portion of the hydraulic cylinder 13 such that its operating portion 22a projects forward from the front surface 2Ra. The return limit switch 22 is turned on when its operating portion 22a is pressed to the rear side of the outer mast 2R. Further, a first emergency proximity switch 23 is provided above the return limit switch 22 with its detecting portion 23a adjacent to the front surface 2Ra.
Then, the first emergency proximity switch 23 is
When the object to be detected is placed in the vicinity of a, it is turned on.

At the upper position on the outer side of the left outer mast 2L, there is provided a rising restricting portion 31 having the same structure as the right outer mast 2R at the same height. Further, on the outer side of the left outer mast 2L, at a position higher than the return limit switch 22 and lower than the first emergency proximity switch 23, the regular proximity switch 32 is provided with the detection unit 32 thereof.
a is provided adjacent to the front surface 2La of the left outer mast 2L. Then, the regular proximity switch 32 is connected to the detection unit 3
When the object to be detected is arranged near 2a, it is turned on. On the outer side of the left outer mast 2L, at a position higher than the first emergency proximity switch 23, the second emergency proximity switch 33 has its detecting portion 33a on the front surface 2.
It is provided adjacent to La. Then, the second very close proximity switch 33 is turned on when the detected object is arranged near the detection unit 33a.

Dogs 34R and 34L are attached to the upper portions of the left and right sides of the lift bracket 5 by screws so as to face rearward. The dogs 34R and 34L serve as the detection body. The front end surfaces of the dogs 34R, 34L are arranged outside the left and right outer masts 2R, 2L, and the front surfaces 2R of the left and right outer masts 2R, 2L.
It is arranged so as to pass a position opposite to a and 2La. Then, when the lift bracket 5 moves up and down, the dog 34R has a tip end surface for turning on the first emergency proximity switch 23. Further, the dog 34R engages with the operating portion 22a of the return limit switch 22 to turn on the return limit switch 22.
When the lift bracket 5 moves up and down, the dog 34L has its tip end surface for turning on the regular proximity switch 32 and the second emergency proximity switch 33.

At the lower left and right sides of the lift bracket 5,
The engaging portions 35R and 35L are the left and right outer masts 2, respectively.
The outer masts 2R and 2L are formed so as to project outward from the R and 2L and extend to the front surfaces 2Ra and 2La of the outer masts 2R and 2L. Then, when the lift bracket 5 rises, the stoppers 1 are arranged such that the rear side of the upper surface thereof is located at the protruding position of the left and right lift restricting portions 21 and 31 when the lift brackets 5 are raised.
It contacts the front part of the lower surface of No. 2. As a result, the lift of the lift bracket 5 is blocked by each stopper 12. Then, the engaging portions 35R, 3 of the lift bracket 5
In a state in which 5L comes into contact with the stopper 12 and stops, the upper ends of the left and right inner masts 3R, 3L and the upper end of the container C placed on the fork 7 are arranged below the overhead line K sufficiently. In this state, as shown in FIG. 3, the dog 34R is disposed above the first emergency proximity switch 23 and the dog 34L is disposed above the second emergency proximity switch 33. The two engaging portions 35R and 35L are formed to have a strength such that they are not damaged even if they collide with the stopper 12 when the lift bracket 5 is raised at the maximum rising speed.

Next, the electrical configuration will be described. Figure 5
As shown in FIG. 3, on the input side of the controller 41, the lift, tilt and shift operation levers S1 to S3, the stopper limit switch 20, the return limit switch 22, the first emergency proximity switch 23, and the regular proximity switch 32 are provided. And a second very close switch 33 are connected. Each of the operation levers S1 to S3 outputs a signal indicating the operation amount of the lever to the controller 41. The limit switch 20 for the stopper is the stopper 12
The stopper detection signal is output to the controller 41 by detecting the bar 19 of FIG. When the return limit switch 22 and the first emergency proximity switch 23 detect the dog 34R, they output a right dog detection signal to the controller 41. When the regular proximity switch 32 and the second emergency proximity switch 33 detect the dog 34L, they output a left dog detection signal to the controller 41.

On the output side of the controller 41, the control valves 42-4 corresponding to the respective operation levers S1-S3 are provided.
4 are connected. Control valve 42 is line 4
5, 46 to the lift cylinder 4, and the control valve 43 to the tilt cylinder 8 via lines 47 and 48.
In addition, the control valve 44 is connected to the shift cylinder 51 via conduits 49 and 50. Further, the control valves 42 to 44 are connected to the oil pump 5 via the pipe line 52.
3, the hydraulic oil is supplied from the oil pump 53 to the control valves 42 to 44. Further, the control valves 42 to 44 are connected to a drain tank 55 via a pipe 54, and the control valves 42 to 4 are connected.
The hydraulic oil is discharged from 4 to the drain tank 55.
An unload valve 56 is provided at a portion of the conduit 52 that supplies hydraulic oil to the control valve 42. The unload valve 56 is configured to stop the supply of hydraulic oil supplied to the control valve 42 based on a command from the controller 41.

The pipelines 49 and 50 have the pipeline 5 in the middle of the route.
It is branched by connecting 7,58. These branched pipe lines 57 and 58 are connected to the hydraulic cylinder 16. Further, an electromagnetic valve 59 as a switching means is provided on the cylinder 16 side from the branch point of the pipeline 50.
Further, an electromagnetic valve 60 as a switching means is provided in the conduit 58. Each solenoid valve 59, 60 is connected to the lift control switch 10 provided in the cab. The other end of the lift control switch 10 is connected to the power supply 61. A timer circuit 62 is provided between the power supply 61 and the switch 10.

The controller 41 includes the operation levers S1 to S
A command signal is output to the control valves 42 to 44 based on the operation amount of No. 3. The control valve 42 expands and contracts the lift cylinder 4 based on the command signal, and the control valve 43 expands and contracts the tilt cylinder 8 based on the command signal. The control valve 44 expands and contracts the shift cylinder 51 or the hydraulic cylinder 16 based on the command signal.

That is, when the lift control switch 10 is off, the solenoid valves 59 and 60 allow the working oil to flow to the shift cylinder 51 side. And lift switch 1
When 0 is turned on, the spools of the solenoid valves 59 and 60 are switched, and the hydraulic oil is made to flow to the hydraulic cylinder 16.

When the lifting control switch 10 is turned on,
The timer 62 is adapted to turn on. Then, after a lapse of a predetermined time, the timer 62 operates to turn off the power. At this time, the lift control switch 10 is automatically turned off, and the spools of the solenoid valves 59 and 60 are switched to the direction in which the hydraulic oil flows to the shift cylinder 51.

The controller 41 uses the limit switch 2
When 0 is off, the unload valve 56 is operated or stopped based on signals from the return limit switch 22, the first emergency proximity switch 23, the regular proximity switch 32, and the second emergency proximity switch 3. It is like this.

That is, when either the regular proximity switch 32, the first emergency proximity switch 23 or the second emergency proximity switch 33 is turned on while the limit switch 20 is off, the controller 41 is based on this signal. Operates the unload valve 56 to stop the supply of hydraulic oil from the oil pump 43 to the control valve 42. At this time, the oil pump 53 continues to operate. or,
When the return limit switch 22 is turned on in this state, the operation of the unload valve 56 is stopped, and the operating oil is supplied again from the cargo handling pump 53 to the control valve 42. As a result, the lift cylinder 4 can be driven again.

On the contrary, when the limit switch 11 is turned on, the controller 41 operates the normal proximity switch 32,
The unload valve 56 is not operated based on signals from the first emergency proximity switch 23, the second emergency proximity switch 33, and the return limit switch 22. As a result, the lifting height of the lift bracket 5 is not restricted, and normal lifting and lowering can be performed.

Next, the operation of the forklift lifting control device constructed as described above will be described. First, when unloading the container C of a freight car that has entered the service line,
Before the forklift 1 enters the lead-in line, the operator turns on the lift control switch 10 at the driver's seat 9 and operates the shift operation lever S3. Then, the hydraulic oil is hydraulic cylinder 1
6 and the stopper 12 rotates to be positioned at the regulating position. At this time, the limit switch 20 is in the off state.

When the stopper 12 is positioned at the regulated position, the timer circuit 62 starts clocking, and when a predetermined time elapses, the timer circuit 62 cuts off the power and the solenoid valve 5
The supply of the power supply 61 to 9, 60 is stopped. Then, the spools of the solenoid valves 59 and 60 are switched, and the working oil flows to the shift cylinder 51 side. That is, when the shift operation lever S3 is operated, the shift cylinder 51 is driven, so that the fork 7 is brought into a shiftable state. Then, the operator operates each of the operation levers S1 to S3,
Perform various work.

When the forklift 1 passes under the overhead line K and reaches the freight car in the lead-in line, the container C on the freight car is unloaded. At this time, raise the fork 7 too much,
When the dogs 34R and 34L of the lift bracket 5 are arranged at the positions detected by the service proximity switch 32, the service proximity switch 32 is turned on. As a result, the controller 41
Operates the unload valve 56, the supply of hydraulic oil from the oil pump 53 to the control valve 42 is stopped, and the lifting of the lift bracket 5 is stopped. Therefore, the upper ends of the container C or the inner masts 3R and 3L do not interfere with the overhead line K.

Forklift 1 with container C unloaded
Goes under a catenary line K from a service line to a predetermined loading place with the container C placed. When the forklift 1 arrives at the loading place, the worker lifts the lift control switch 10
Is turned on again, the operation lever S3 is operated, the piston rods 16a of the left and right hydraulic cylinders 16 are retracted, each stopper 12 is placed in the release position, and the limit switch 20 is turned on.

At the loading place, the lift bracket 5 is lifted to load the container C onto the already loaded container C. In this state, limit switch 2
Since 0 is turned on, the normal proximity switch 32, the first
The proximity switch 23 or the second proximity switch 33 does not detect the dogs 34R and 34L, and the unload valve 56 does not operate. Therefore, since the fork 7 can be lifted to the maximum lift, the container C unloaded from the freight car can be stacked on the already loaded container C.

When the forklift 1 enters the lead-in line again for unloading the load, the operator turns on the lift control switch 20 again and operates the operation lever S3 to extend the hydraulic cylinder 16. As a result, the stopper 12 is again placed in the restricting position, and the lift of the fork 7 is restricted.

When the normal proximity switch 32 does not operate normally due to long-term use and the lift bracket 5 is not stopped by the normal proximity switch 32, the first emergency proximity switch 23 is moved to the next. Is detected. As a result,
The unload valve 56 is actuated based on the signal from the first emergency proximity switch 23 to stop the lift bracket 5 from further rising. Therefore, even when the lift bracket 5 is not detected by the regular proximity switch 32, the interference of the inner mast 3 or the container C with the overhead line K is prevented.

When the lift bracket 5 is not stopped by the first emergency proximity switch 23, it is detected next to the second emergency proximity switch 33. As a result, the unload valve 56 operates based on the signal from the second very close switch 33 to stop the lift bracket 5 from further rising. Therefore, even if the lift bracket 5 is not detected by the regular proximity switch 32 or the first emergency proximity switch 23, the inner mast 3 or the container C is prevented from interfering with the overhead line K.

Further, the dog 34 of the lift bracket 5 is
If the R and 34L do not stop at the position to be detected by the second emergency proximity switch 33, the lift bracket 5
The engaging portions 35R, 35L contact the stopper 12 and are mechanically stopped. Therefore, even when the lift bracket 5 is not detected by the regular proximity switch 32, the first emergency proximity switch 23, and the second emergency proximity switch 33, the inner mast 3 or the container C is prevented from interfering with the overhead line K. .

As described above, according to the lift control device for a forklift of the present embodiment, when the forklift 1 enters the loading line from the lead-in line and, conversely, enters the lead-in line from the load-holding place, the worker is in the cab. By operating the lift control switch 10 and the shift operation lever S3, the stopper 12 capable of mechanically stopping the lift of the lift bracket 5 can be switched and arranged. Therefore, the operator can regulate the lift of the fork 7 only by operating the lift regulation switch 46 in the cab 9 without going down from the cab 9 as in the conventional case. As a result, it is possible to efficiently and swiftly perform the unloading work, the laying work, etc., which must be performed while the wagons are coming in and out and without contacting the overhead wire K. Moreover, since it is driven by the hydraulic cylinder 16, it is possible to reduce power consumption as compared with the case where the stopper 12 is driven by an electric cylinder or the like. Further, by rotating the stopper 12 with the hydraulic cylinder 16, the stopper 12 can be easily positioned at the restricting position and the releasing position. Therefore, the mechanism for driving the stopper 12 can be simplified, and the space for installing the mechanism can be reduced.

Further, since the hydraulic oil is supplied from the same oil pump 53 and control valve 44 as the lift cylinder 4, tilt cylinder 8 and shift cylinder 51, it is necessary to provide a new control valve for driving the hydraulic cylinder 16. And the structure can be simplified. Moreover, since the pipes 49 and 50 connected to the shift cylinder 51 are branched by the pipes 57 and 58 to connect the hydraulic cylinder 16, the operator can easily operate the shift operation lever S3 to position the stopper 12 at the regulating position. And the release position.

Further, solenoid valves 59 and 60 are provided in the pipe lines 50 and 58 to the shift cylinder 51 and the hydraulic cylinder 16,
After the supply of the hydraulic oil to the hydraulic cylinder 16 is started, the spool of the solenoid valves 59 and 60 is switched after a predetermined time by the timer circuit 62 to supply the hydraulic oil to the shift cylinder 51. Therefore, it is not necessary to manually switch the solenoid valves 59 and 60, and the operability can be improved.

Further, the timer circuit 62 automatically shifts the fork 7 by the operating lever S3 after the predetermined time. Therefore, when the operating lever S3 is operated to shift the fork 7 after a predetermined time, the fork 7 is always shifted,
It is possible to prevent the stopper 12 from being operated by mistake. Therefore, if the operating lever S3 is operated under the overhead line K or the like after a predetermined time, it is possible to prevent the stopper 12 from being accidentally moved to the release position, so that the fork 7 rises beyond the predetermined position and the overhead line K It is possible to prevent contact with and improve safety.

When the limit switch 20 is turned off and the stopper 12 is placed in the regulating position, each switch 2
The controller 41 operates the unload valve 56 based on the detection signals from 2, 23, 32, and 33 to stop the lifting of the fork 7. Therefore, the rise of the fork 7 can be stopped before the engaging portions 35L, 35R mechanically contact the stopper 12, so that the life of the stopper 12 and the engaging portions 35L, 35R can be improved. Moreover, the plurality of switches 22,
23, 32, and 33 are provided, even if one switch fails due to a failure or the like, the engaging portions 35L, 35
The rise of the fork 7 can be reliably stopped before R contacts the stopper 12.

The present invention is not limited to the above embodiments, but may be configured as follows, for example, without departing from the spirit of the invention. (1) In the above embodiment, the supply of the hydraulic oil supplied to the lift cylinder 4 was stopped by the unload valve 56. However, for example, the control valve 42 is supplied to the lift cylinder 4 based on the command signal from the controller 41. The hydraulic oil used may be stopped.

(2) In the above embodiment, the proximity switch 23 for detecting the dogs 34R, 34L of the lift bracket 5,
Although three 32 and 33 are provided, one or two may be provided, and four or more may be provided.

(3) In the above embodiment, the hydraulic cylinder 16
The pipe lines 57 and 58 for supplying and discharging the hydraulic oil are connected to the pipe lines 49 and 50 of the shift cylinder 51, but the pipe lines 45 and 46 of the lift cylinder 4 and the pipe line 4 of the tilt cylinder 8 are connected.
It may be connected to 7,48.

(4) In the above embodiment, the return switch 22 may be provided in the operator's cab and manually operated by the operator. (5) In the above embodiment, the lift control switch 10 is connected to the controller 41, and the control valve 44 is controlled based on a command from the controller 41 to switch the hydraulic oil supplied to the shift cylinder 51 or the hydraulic cylinder 16. May be. In this case, the control valve 44
Is the switching means.

(6) In the above-described embodiment, the present invention is applied to each forklift 1 in which any one of the following operations is performed as the fork drive: raising and lowering and tilting of the fork 7, raising and lowering and shifting the fork 7, and raising and lowering the fork 7. Good.

The technical ideas other than the claims that can be understood from the above-described embodiments will be described below along with their effects. (1) In the lift control device for a forklift according to any one of claims 1 to 3, detection means for detecting the lift bracket 5 is provided on the outer masts 2R, 2L, and the fork is caused by the restriction member based on a detection signal from the detection means. An unload valve 56 for controlling the hydraulic pressure of the lift cylinder 4 to stop the fork 7 below the position where the fork 7 stops is provided.

According to this lift regulation device for a forklift, the fork 7 is stopped based on the detection signal from the detection means at a position below the position where the fork 7 stops due to the restriction member engaging the lift bracket 5. Can be made.

The term "stopper" used in this specification is defined as follows. The "stopper" includes not only a member that is positioned between the regulation position and the release position by rotating as shown in the above embodiment, but also a member that is positioned between the regulation position and the release position by sliding or the like. Is the meaning.

[0064]

As described above in detail, according to the first aspect of the invention, by operating the regulating member with the hydraulic cylinder, the regulating member can be operated easily and surely, and at the same time, Since the control hydraulic cylinder is connected to the control valve to which the fork hydraulic cylinder is connected, the structure can be simplified. According to the second aspect of the invention, the hydraulic oil supplied to the fork or regulating hydraulic cylinder can be easily switched by the solenoid valve. According to the invention described in claim 3, the hydraulic cylinder operated by the fork operating means can be switched by the timer circuit.

[Brief description of drawings]

FIG. 1 is a side view showing a forklift equipped with a lifting control device.

FIG. 2 is a front view of a mast portion provided with a lifting control device.

FIG. 3 is a side view of a right outer mast including a lifting control device.

FIG. 4 is a plan view showing a lifting control device provided on the right outer mast.

FIG. 5 is a schematic block diagram showing an electrical configuration.

FIG. 6 is a perspective view showing a lift restricting portion of a conventional example.

[Explanation of symbols]

2R, 2L ... Outer mast, 4 ... Lift cylinder as hydraulic cylinder for fork, 5 ... Lift bracket, 7
... Fork, 8 ... Tilt cylinder as hydraulic cylinder for fork, 9 ... Operator's cab, 10 ... Lifting regulation switch as switching operation means, 16 ... Hydraulic cylinder as regulating hydraulic cylinder, 42-44 ... Control valve,
51 ... Shift cylinder as hydraulic cylinder for fork, 53 ... Oil pump as hydraulic oil supply source, 62 ...
Timer circuit, S1 to S3 ... Fork operating means.

Claims (3)

[Claims] 1. A forklift in which a fork is attached to a lift bracket that can be raised and lowered along an outer mast, and the fork is moved up and down together with the lift bracket. And a fork hydraulic cylinder that drives the fork based on the operation of the fork operating means, and a control valve that controls the hydraulic oil supplied from the hydraulic oil supply source to the hydraulic cylinder based on the operation of the fork operating means. A restricting member provided on the outer mast, the restricting member being capable of being positioned at two positions: a restricting position for engaging the lift bracket to stop the fork and a releasing position not engaging with the lift bracket, and the fork operating means. Move the control member forward based on the operation. To supply hydraulic oil from a control hydraulic cylinder that is positioned at two positions and a control valve that is provided in the cab and that is connected to the control hydraulic cylinder to either the fork hydraulic cylinder or the control hydraulic cylinder. A lift regulation device for a forklift, comprising switching operation means for operating, and switching means for supplying hydraulic oil to either a fork hydraulic cylinder or a restriction hydraulic cylinder based on the operation of the switching operation means. 2. The lift control device for a forklift according to claim 1, wherein the switching means is a solenoid valve provided between the control valve and the fork hydraulic cylinder and between the control valve and the control hydraulic cylinder. . 3. A timer circuit is connected to the switching operation means, and when the supply of hydraulic oil to the regulating hydraulic cylinder is started based on the operation of the switching operation means, the timer circuit starts timing. 3. The lift control device for a forklift according to claim 2, wherein the solenoid valve is switched so as to supply hydraulic oil to the fork hydraulic cylinder after a predetermined time has elapsed based on the timing of the timer circuit.