JPH0547190Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is a cargo handling vehicle of the type in which a driver lifts and lowers with a lifting device, such as an order picker vehicle or rack fork (hereinafter simply referred to as an order picker vehicle, etc.).
In particular, in custom-made vehicles where the lift cylinder is raised and lowered by remotely controlling the starting and stopping of the hydraulic pump and the opening and closing of the valve provided in the return line on a platform, it is particularly important to This invention relates to a shock absorbing device that is effective in preventing impact when stopped at an edge.

(Prior art) Generally, in this type of custom-made vehicle,
An electromagnetic on-off valve called a shockless valve is provided in the return line of the lift cylinder. This electromagnetic shockless valve slowly switches the spool during the downward movement of the lift cylinder to gradually increase or decrease the flow of hydraulic oil returning from the lift cylinder to the oil tank. It also functions to suppress the occurrence of shock when the vehicle stops. By the way, the switching operation of this shortless valve is generally performed by turning on and off an automatic return type push button switch on the platform. Therefore, if the pushbutton switch is released while descending, the shock valve will operate normally and the lift can be stopped in a buffered state. There is a problem in that when the device reaches the lower end, the shockless valve cannot function and the device stops with a shock.

Therefore, it is known that urethane rubber is used as a means for alleviating the impact at the descending end.
This is achieved by attaching urethane rubber as a buffer member to the lower surface of the attenuated tie beam of the inner mast that is connected to the upper end of the rod of the lift cylinder, and this urethane rubber elastically abuts against the upper end surface of the lift cylinder at the lower end. Thus, the shock at the lower end is absorbed, and such a system is disclosed in, for example, Japanese Utility Model Application Publication No. 170198/1983.

(Problem that the invention aims to solve) However, with the above-mentioned shock absorbing method using an elastic body, it is difficult to adjust the left and right contact surfaces, especially when the lift cylinder has two left and right types, and due to differences in load, etc. The cushioning effect is not constant due to uneven contact of the urethane rubber, the inability to obtain a sufficiently wide contact surface due to the small diameter of the cylinder, etc., and it is not necessarily effective in reducing impact. It is difficult to tell, and there are problems such as the amount of wear of the left and right urethane rubber becoming uneven.

Therefore, in view of the above problems, the purpose of the present invention is to provide a shock absorbing device that can effectively prevent impact when stopping at the descending end of a custom-made vehicle, etc. by using a shock valve. shall be.

(Means for solving the problem) The present invention for solving the above problem has a function to gradually increase or decrease the flow rate at the start and stop of descent into the return pipe connecting the lift cylinder and the oil tank. In custom-made vehicles equipped with electromagnetic shockless valves, the operating circuit connecting the solenoid of the shockless valve and the battery includes a lowering switch that is manually turned on and off, and a lifting device that is connected to the lowering end. before reaching
The gist is that a falling edge detection switch that can be turned off is provided.

(Function) When the lowering switch is turned on to lower the lifting device on the platform, the solenoid of the shotless valve is energized and the spool of the shotless valve is switched to open the passage. This spool switching operation is performed slowly, and the hydraulic fluid in the lift cylinder gradually flows out, so that the lowering operation is started smoothly without any impact. If the elevator approaches the lowering end while the driver continues to press the lowering switch, the lowering end detection switch is turned OFF, cutting off the power to the solenoid of the shotless valve. , the spool of the shockless valve is switched to close the passage. At this time, the switching operation is performed slowly, and the hydraulic fluid in the lift cylinder is gradually discharged, so that the lifting device is stopped at the lower end without any impact.

(Example) Hereinafter, an example of the present invention will be specifically described based on the drawings. FIG. 5 schematically shows a reach-type order picker vehicle as an example of a vehicle to which the present invention is applied. It is attached so that it can be raised and lowered together with the loading platform 36.

Figure 1 shows the platform 35 and loading platform 36.
This figure shows a hydraulic circuit for a lift cylinder 1 for raising and lowering an elevating device consisting of, etc., and this embodiment shows a case where there are two lift cylinders 1 on the left and right sides. The hydraulic pump 2 is driven by an electric motor 3 which is controlled to start and stop by operating a lift switch (not shown) on the platform 35, and the hydraulic pump 2 pumps oil from the oil tank 4. The lift cylinder 1 is raised by supplying the raised hydraulic oil to the lift cylinder 1 through a check valve 6 provided in a pressure pipe 5. A flow control valve 7 is built into the bottom of one of the lift cylinders 1, and a down control valve 8 is built into the bottom of the other lift cylinder 1. The flow of hydraulic fluid in and out is controlled. 9 is a relief valve.

On the other hand, a return conduit 10 connecting the lift cylinder 1 and the oil tank 4 is provided with an electromagnetic shock valve 11 that functions to prevent shock during the downward movement. The details of this shockless valve 11 will be explained below based on FIG. 2. As shown, a spool 13 incorporated into the valve body 12
is adapted to open and close the communication passage 18 between the tank port 16 and the cylinder port 17 on the left side of the figure by being switched by the cooperation of the solenoid 14 and the return spring 15, and the switching The operating speed is slowed by a switching speed limiting mechanism 19 located on the right side of the figure. The switching speed limiting mechanism 19 includes an oil chamber 20 formed in the valve body 12, a piston 22 with an orifice 21 integrally provided on the spool 13 so as to slide within the oil chamber 20, and an oil chamber 20.
0 and a communication path 23 for communicating the cylinder port 17 with the spool 13.
At the time of switching, the switching speed is limited by restricting the outflow and inflow of hydraulic oil into the oil chamber 20 by the orifice 21.

FIG. 3 shows an electric circuit for controlling the shortless valve, and is a lowering control circuit in which a fuse 24, an automatic return type lowering push button switch 25, a lowering end detection limit switch 26, and a lowering relay 27 are inserted in series. The fuse 28, the normally open contact 27a of the lowering relay 27, and the solenoid operating circuit in which the solenoid 14 of the shock valve 11 are inserted in series are connected in parallel to the battery 29. And push button switch 2 for lowering
5 is provided at an operable position on the platform 35, and a limit switch 26 for detecting the lowering end is provided at the lower side of the fixed mast (usually the outer mast) 34, as shown in FIG. , is adapted to be actuated by a plate 30 attached to a platform 35. Moreover, the limit switch 26 is specifically the mast 3
4 through the switch bracket 26a and the bolt 3
1 is height-adjustably mounted, so that by changing its position, the lowering end of the platform 35 can be changed.

This embodiment is configured as described above,
The effect will be explained below.

Now, when the driver presses the lower push button switch 25 on the platform 35 to turn it on, the lower relay 27 is energized and its normally open contact 27a is turned on, so the solenoid 14 is energized. , the spool 13 of the shockless valve 11 is switched to the passage open side (left side in the figure), but this switching operation is performed by the switching speed limiting mechanism 19 as described above.
It is carried out slowly by the function of That is, the movement speed of the spool 13 is limited by the function of limiting the amount of oil flowing out from the oil chamber 20 by the orifice 21 of the piston 22, and the opening action of the passage by the valve portion 13a of the spool 13 is gradually performed. The hydraulic oil is gradually discharged from the oil tank 1 to the oil tank 4. Therefore, the lifting device can start its lowering operation without any impact.

When the lifting device approaches the lowering end with the push button switch 25 being pressed, the plate 30 of the platform 35 comes into contact with the limit switch 26 for detecting the lowering end and turns it off. The relay 27 is de-energized, its normally open contact 27a turns OFF, and the solenoid 14
Power is cut off. Therefore, the spool 13 of the shotless valve 11 is switched to the passage closing side (on the right side in the figure) by the return spring 15, but this switching operation is slow due to the function of restricting the flow of hydraulic oil into the oil chamber 20 by the orifice 21. Therefore, the hydraulic oil is gradually discharged from the lift cylinder 1 to the oil tank 4, and the elevating device can be stopped at the lower end without any impact.

Note that even if the driver releases the pushbutton switch 25 and turns it OFF during the descent to stop at the desired position, the spool of the shotless valve 11 will be closed in the same way as when stopping at the descending end. 13 is performed slowly, resulting in a stop without impact.

Although this embodiment has been described with reference to a reach-type order-picker vehicle, the present invention is not limited to this, and can be applied to any vehicle in which the driver moves up and down with a lifting device. Further, the descending switch and the descending end detection switch are not limited to the types described in the embodiments, and can be changed as appropriate.

(Effects of the invention) As detailed above, according to the invention, the lifting device can be stopped without causing any impact at the lowering end while the lowering switch remains on. In addition, accidents such as falling cargo can be prevented, and the driver no longer needs to be careful about stopping at the end of the descent, which relieves him from mental fatigue. In addition, since this invention uses a shockless valve to prevent shock at the descending end, compared to the conventional absorption method using urethane rubber, it can always provide a constant buffering effect and last for a long time. It is possible to maintain stable performance over a long period of time, and can be easily realized by adding a lowering end detection switch, and when the mounting position of the switch is adjustable, the lowering of the lifting device can be adjusted as necessary. The edges can be changed freely.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a hydraulic circuit diagram for operating the lift cylinder, Fig. 2 is a sectional view showing the shockless valve, Fig. 3 is an electrical circuit diagram for operating the shockless valve, and Fig. FIG. 4 is a partial perspective view showing how the limit switch for detecting the lowering end is attached, and FIG. 5 is a schematic perspective view of the reach type order picker vehicle. 1...Lift cylinder, 10...Return pipe line, 1
DESCRIPTION OF SYMBOLS 1...Shockless valve, 14...Solenoid, 19...Switching speed limiting mechanism, 25...Push button switch for lowering, 26...Limit switch for detecting the lowering end.

Claims (1)

[Scope of utility model registration request] In a custom-made vehicle equipped with an electromagnetic shockless valve that functions to gradually increase or decrease the outflow amount at the start and stop of descent in the return pipe connecting the lift cylinder and the oil tank, the solenoid of the shockless valve is used. When descending in order-picker vehicles, etc., the operating circuit connecting the battery and battery is equipped with a descending switch that is manually turned on and off, and a descending end detection switch that is turned off before the lifting device reaches the descending end. shock absorber.