JPH0617839Y2 - Forklift lifting device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] In the present invention, an oil control valve for lifting the fork and a cargo handling lever and a remote control lever for operating the fork are provided on both the driver's seat side and the fork side, respectively. The present invention relates to a fork lift remote control device for a forklift that allows the fork to be quickly lowered when the remote control lever is operated.

[Prior art]

A remote-controlled battery forklift used for aerial work is a forklift that allows a driver to ride on a fork that moves up and down along a mast, and to operate the lifting on the fork as well (for example, the actual opening). 57
-11111)).

As shown in FIG. 9, a forklift of this type normally has a remote device 9 for raising and lowering a backrest 94 on the side of the fork.
Have five. Reference numerals 11 and 13 in FIG.
It is a cargo handling lever for lifting the fork on the side.

Thus, there are mainly the following two types as the lifting / lowering remote device. One is an electromagnetic valve system in which an electromagnetic valve is installed in the hydraulic circuit and the push button switch is operated in the lifting remote device on the fork, and the other one is the driver's seat side on the lifting remote device on the fork. It is a remote control lever system that uses the same oil control valve and opens and closes the hydraulic circuit with a remote control lever.

The electromagnetic valve system has a configuration as shown in FIGS. 4 and 5. That is, this fork lifting device is provided with the oil pump 4 that pumps the working oil 40 in the oil tank 4.
1, oil control valve 1 and lift cylinder 2
And a solenoid valve 81 that is remotely operated on the fork,
And 82. The oil control valve 1 is
It has a section spool 10 for supplying or stopping working oil to the lift cylinder 2, and a cargo handling lever 11 for operating the section spool 10.

Further, the oil control valve has a section spool 12 for supplying or discharging working oil to a tilt cylinder (not shown) and a tilt lever 13 for operating the section spool 12. The electromagnetic valve 81 is a valve for remotely operating the ascent of the lift cylinder 2 on the fork, and the electromagnetic valve 82 is also a valve for remotely operating the ascent of the lift cylinder 2 on the fork. In FIG. 4, reference numeral 21 is a cylinder rod for lifting and lowering the fork, 22 is a pipe for supplying and discharging working oil, 83 is an accumulator, and 42 is a check valve.

When the lift cylinder 2 is moved up and down by this device, as shown in FIGS. 4 and 5, when the cargo handling lever 11 is operated in the normal driver's seat, the valve of the section spool 10 opens, and the pump motor switch LS is opened.
L and LST are turned on, and the contactor MP operates the oil pump 41. As a result, the working oil 40 is supplied into the lift cylinder 2 from the section spool 10, the pipe 14, and the supply / discharge pipe 22, the cylinder rod 21 is raised, and the fork is raised. Next, at the time of lowering, the section spool 10 is operated by the cargo handling lever 11 so that the pipes 141 and 14 communicate with each other, and the working oil 40 is returned from the pipe 822 into the oil tank 4.
As a result, the cylinder rod 21 descends and the fork descends.

Next, when the remote operation is performed on the fork, the section spools 10 and 12 are set to the neutral position and the switch 81S for the electromagnetic valve 81 is pushed, so that the working oil 40 is transferred to the pipe 15, the electromagnetic valve 81, the pipe 811,
After being sent to the lift cylinder 2, the fork is lifted. On the other hand, when lowering the fork, pressing the switch 82S for the electromagnetic valve 82 causes the working oil 40 to move from the lift cylinder 2 to the pipes 22, 81.
1, 821, the electromagnetic valve 82, and the pipe 822 to be returned, and the fork descends. In FIG. 5, B is a battery, F is a fuse, KS is a forklift key switch, and D is a diode.

On the other hand, the latter remote control lever system has a structure as shown in FIGS. 6 to 8. That is, in this system, the oil control valve 3 similar to the operating oil 1 on the driver's side is provided on the fork. The oil control valve 3 has a section spool 30 similar to the section spool 10 for the operating oil 1 on the driver's side, and a remote control lever 31 for operating the section spool 30.

Then, the supply / discharge pipe 22 of the lift cylinder 2 and the delivery side pipe 32 of the section spool 10 are connected.
In addition, the delivery side pipe 15 of the section spool 10 is
It is connected to the feeding side of the section spool 30. Further, the discharge side pipe 33 of the section spool 30 is connected to the discharge pipe 43. Other than that, the hydraulic circuit configuration is the same as that of the electromagnetic valve system.

Further, the oil control valve 30 as a lifting / lowering remote device has a link 301, a shaft pin 3 as shown in FIG.
It is mechanically connected to the remote control lever 31 via 11. Further, below the remote control lever 31, a contactor 302 pivotally attached to the shaft pin 311 and rotating integrally with the remote control lever 31 is provided. A limit switch 34, which serves as a pump switch for raising the fork, is disposed on the vehicle body in front of the contact 302.

Next, when the fork is moved up and down by this device, first, the operation on the driver's side is to move the fork up and down by operating the cargo handling lever 11 as in the electromagnetic valve system.
On the other hand, when operating remotely on a fork,
The oil control valve 1 is set in the neutral position, and the oil control valve 3 is operated by the remote control lever 31. That is, the remote control lever 31 shown in FIG.
The contact 30 at the lower end of the fork
2 turns on the limit switch 34. By this,
As shown in FIG. 7, the oil pump 41 is operated by the contact MP.

Therefore, the working oil 40 enters the lift cylinder 2 through the oil control valve 1, the pipe 15, the oil control valve 3, and the pipes 32, 22 to push up the cylinder rod 21 and raise the fork. On the other hand, when lowering the fork, the oil control valve 3
The remote control lever 31 is operated to connect the pipes 32 and 331 to each other, so that the working oil 40 in the lift cylinder 2 is transferred to the pipes 22, 32, the section spool 30, and the pipe 3.
After returning through 31, 33 and 43, the fork is lowered.

[Problems to be solved]

 However, both of the above formulas have the following drawbacks.

That is, in the former electromagnetic valve system, since the hydraulic circuit is rapidly opened and closed by the electromagnetic valve both at the time of ascent and descent, a large impact is generated at the time of starting and stopping when lifting the fork. Although a shock absorber such as the accumulator 83 is provided, it is difficult to adjust the pressure due to a large pressure difference in the pipe when the load is applied and when the load is not applied.

On the other hand, in the latter remote control lever system, since the oil control valve 3 as a remote lifting device is provided on the fork side, it is necessary to extend the pipes 32, 15 and 33 from the machine base of the forklift to the fork side. Is. Since the fork moves up and down, it is necessary to make the pipe long enough so that there is a margin even when the fork is fully raised. And, since the length thereof is twice as high as the height of the fork up to the maximum, it becomes very long. Further, this length must be changed depending on the lift of the mast depending on the type of fork, so that it becomes particularly long in a high lift mast.

Therefore, the hydraulic circuit in this remote control lever system has a very large piping resistance when it is moved up and down by the remote control lever on the fork. Therefore, when the fork is lowered by the remote control lever in a no-load state, the returning speed of the working oil becomes small, and the fork can be lowered only at a low speed of about one-third of that under load.

In view of the above problems of the conventional device, the present invention is to provide a forklift lifting / lowering remote device that has less impact when the fork is lowered and can increase the lowering speed.

[Means for solving problems]

The present invention has a loading lever for lifting the fork on the driver's side, and a remote control lever for remotely operating the lifting of the fork on the fork that moves up and down along the mast. In a forklift having an oil control valve for supplying or discharging working oil to or from a lift cylinder for lifting a fork, in a pipe connecting the lift cylinder and the oil control valves of the cargo handling lever and the remote control lever, respectively. Is a remote lifting / lowering device for a forklift characterized in that a bypass passage dedicated to fork lowering is provided, and an opening / closing valve operated on the fork side is provided in the bypass passage.

What should be noted in the present invention is a lift cylinder,
In the middle of the pipe connecting the oil control valve on the driver's side and the oil control valve on the fork side,
This is because a bypass passage dedicated to the lowering of the fork was provided and an opening / closing valve was provided in the bypass passage.

Therefore, the bypass passage is directly connected to the working oil supply / discharge nozzle of the lift cylinder, or is connected to the return pipe of the oil control valve on the driver's side to connect the lift cylinder and the oil control valves. Connect to the connecting pipe. The bypass passage is preferably provided at the shortest distance between the lift cylinder and the oil tank so that the bypass passage can be shortened. An electromagnetic valve is preferably used as the opening / closing valve of the bypass passage. This on-off valve is operated on the fork side by using a limit switch linked to the remote control lever. Further, it is preferable that a throttle is provided in the bypass passage for adjusting the discharge of the operating oil, that is, for adjusting the descending speed of the fork.

[Action]

In the present invention, when raising and lowering the fork on the driver's seat side, it is performed in the same manner as in the prior art. Further, when the fork is lifted and lowered on the fork side, it is carried out by the remote control lever system of the above-mentioned prior art, but what is important here is that the fork is lowered by using the opening / closing valve of the bypass passage together.

That is, when the fork is lowered, the remote control lever operation in the remote control lever system is performed. In parallel with this, the opening / closing valve of the bypass passage is opened, and the fork is lowered by both the oil control valve on the fork side and the bypass passage.

However, at this time of descending, the distance between the lift cylinder and the oil tank in the bypass passage is much shorter than that in the working oil passage that passes through the oil control valve on the fork side. Is very few. Therefore, the working oil returns from the lift cylinder quickly, and the fork descends quickly.

〔effect〕

As described above, according to the lifting / lowering remote device of the present invention, it is possible to increase the descending speed of the fork even in the remote operation on the fork. Also, since the bypass passage is opened after opening the oil control valve on the fork side, the impact when descending is small. Therefore, cargo handling work can be performed smoothly. The structure is also simple.

〔Example〕

A remote device for raising and lowering a fork according to an embodiment of the present invention will be described with reference to FIGS.

This device comprises an oil tank 4, an oil control valve 1 on the driver's seat side, an oil control valve 3 on the fork side, a lift cylinder 2, and a bypass passage 5.

One end of the bypass passage 5 is connected to the working oil supply / discharge pipe 22 of the lift cylinder 2. Also connected to the pipe 22 are pipes 14 and 32 which are connected to the oil control valves 1 and 3, respectively. The bypass passage 5
May be connected in the middle of the pipe 14 so that the passage from the lift cylinder 2 to the oil tank 4 is as short as possible. Further, the bypass passage 5 is provided with an electromagnetic valve 52 having a check valve as an opening / closing valve and a throttle adjusting valve 51. Other parts of the hydraulic circuit are the same as those of the conventional remote control lever system (FIG. 6).

Next, as shown in FIG. 3, a limit switch 35 for opening and closing the electromagnetic valve 52 of the bypass passage 5 is provided near the oil control valve 3 on the fork side. The limit switch 35 is provided near the remote control lever 31 for operating the section spool 30 and is provided with the limit switch 3 for operating the oil pump 41.
4 are provided in parallel.

Since the device of this example is configured as described above, it has the following effects.

That is, when remotely raising the fork on the fork, the remote control lever 31 is operated as in the remote control lever system.

Next, when the fork is lowered, the remote control lever 31 is pushed downward as shown in FIG. By this,
Section spool 30 of oil control valve 3
At, the pipes 32 and 331 communicate with each other, the working oil in the lift cylinder 2 is discharged, and the fork descends.
At this time, the working oil outflow path is the lift cylinder 2, the pipes 22, 32, the section spool 30, and the pipes 331, 33, 43. The descending speed of the fork at this time is about one-third of the case of operating the cargo handling lever 11 on the driver's side (the same as the conventional remote control lever system).

Therefore, when the remote control lever 31 is pushed to the stroke end in order to further accelerate the descending speed, the contact 3
12 turns on the switch 35, and the electromagnetic valve 52 opens. As a result, the working oil is returned to the oil tank 4 also from the bypass passage 5.

Thus, the piping resistance of the working oil flow in the bypass passage 5 is considerably smaller than the piping resistance of the long distance piping passing through the section spool 30. Therefore, the return of the working oil from the bypass passage 5 is very quick. Therefore, when using only the section spool 30 (first section
When using the bypass passage 5 in combination (second speed)
Speed), a fork lowering speed of about 3 times can be obtained. This speed adjustment can be changed by adjusting the throttle valve 51.

As described above, according to the apparatus of this example, the bypass passage is provided, so that the speed of descending the fork can be increased.

Also, since the fork is not stationary and the bypass passage is not opened suddenly, the oil control valve on the fork side is first used as the first speed, and then the bypass passage is also used, so there is little impact when descending. In addition, the throttle valve 51
Since it is provided, the descending speed can be arbitrarily adjusted according to the type of cargo handling work.

[Brief description of drawings]

1 to 3 show a lifting remote device according to an embodiment, FIG. 1 is a hydraulic circuit diagram thereof, FIG. 2 is an operation electric circuit diagram thereof, FIG. 3 is a conceptual diagram of a lifting remote device, and FIG. Figure and Fifth
FIG. 4 shows a conventional lifting remote device, FIG. 4 shows its hydraulic circuit diagram, FIG. 5 shows an electric circuit diagram, FIGS. 6 to 8 show a conventional lifting remote device, and FIG. 6 shows its hydraulic circuit. FIG. 7 is an electric circuit diagram, FIG. 8 is a conceptual diagram of a lifting / lowering remote device, and FIG. 9 is a perspective view of a battery-powered forklift. 1 …… Oil control valve on driver side, 10 …… Section spool, 11 …… Loading lever, 2 …… Lift cylinder, 3 …… Oil control valve on fork side, 30 …… Section spool, 31 …… Remote control lever , 40 ... hydraulic oil, 5 ... bypass passage, 52 ... electromagnetic valve,

Claims (1)

[Scope of utility model registration request] 1. A cargo handling lever for raising and lowering a fork on the driver's seat side, and a remote control lever for remotely controlling the raising and lowering of the fork on the fork side that is raised and lowered along a mast. Is a forklift having an oil control valve for supplying or discharging working oil to or from the lift cylinder for fork lift, in the middle of the pipe connecting the lift cylinder with the oil control valves of the cargo handling lever and remote control lever. The forklift lifting / lowering device is characterized in that a fork lowering bypass passage is provided in the forklift, and an opening / closing valve operated on the fork side is provided in the bypass passage.