JPH0640237Y2 - Telescopic spreader reach cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a reach cylinder of an extendable spreader which is mounted on a forklift and is mainly used for loading and unloading of marine containers.

(Prior Art) Generally, a sea container is classified into a large size of 40 feet and a small size of 20 feet according to the standard, and the telescopic spreader for handling such two kinds of containers is
As shown in the figure, a pair of left and right rails 2 each having a twist lock pin 3 for suspending a container at the tip end are individually extendably inserted into a horizontally arranged cylindrical rail holder 1.
The reach cylinder 4 is configured to expand and contract. The rail holder 1 is usually attached to a lift bracket of a forklift through a spreader frame (not shown). Further, the reach cylinder 4 is arranged in parallel with the rail holder 1 and the rail 2, and its base end is rotatably supported by a bracket 6 fixed to the rail holder side via a pin 7.
Further, the tip of the piston rod 5 is pinned on the rail side, specifically, on the bracket 9 fixed to the twist lock beam 8.
It is rotatably connected via 10. An example of such an extendable spreader is, for example, Shoukai 58-67896.
No. Gazette and No. Shokai 63-169977.

(Problems to be solved by the invention) When handling a large container, the rail 2 is extended as shown in FIG. 9, and the container C is hung in this state. Especially, in the case of a large container, the weight of the container C is increased. Since the rail is large, the rail 2 may be bent downward as illustrated. When such bending occurs, the rail 2 tends to be pulled out because the position of the twist lock pin 3 is restricted by the hanging hole of the container C.
However, since the span of the rail holder 1 and the rail 2 is regulated by the reach cylinder 4, tensile force acts on the reach cylinder 4, and stress concentrates on the welded portions of the brackets 6 and 9 that are the mounting members. Welding may occur. Then, when the strength of the welded portion is increased to a level capable of sufficiently counteracting the tensile force, the reach cylinder itself may be overloaded and may be damaged.

In view of the above problems, an object of the present invention is to protect the reach cylinder, its mounting portion, and the like from an excessive load when the container is suspended.

(Means for Solving the Problems) The present invention is configured as follows to solve the above problems.

The reach cylinder, which is slidably inserted into the horizontal rail holder, is used to extend and contract the rail, and the base end is supported by the rail holder and the tip of the piston rod is connected to the rail. Has been done.

The reach cylinder holds the piston rod at the specified stroke end position when the tensile force is not applied to the piston rod at the stroke end in the extension direction, and when the tensile force acts on the piston rod, the amount of the tensile force is increased. Correspondingly, a shock-absorbing spring is provided to allow the piston rod to move beyond the specified stroke end.

(Operation) According to the present invention configured as described above, when the reach force of the reach cylinder is not applied to the piston rod,
The reach cylinder is expanded and contracted with a preset stroke, but when the reach cylinder is extended and the container is hung in a state where the rail is extended to correspond to a large container, the rail is loaded by the container load. When the flexure occurs, a pulling force acts on the piston rod of the reach cylinder as the rail is about to be pulled out, so that the piston rod is pulled out beyond the stroke end while the buffer spring is compressed.

That is, the buffer spring always expands and contracts the reach cylinder with a prescribed stroke, and when an excessive load is applied while the container is suspended, the buffer spring absorbs the load and protects the reach cylinder and its mounting portion.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to the drawings. The basic structure of the telescopic spreader is as described with reference to FIG. 8 in the section of the prior art.

Example 1 First, Example 1 shown in FIGS. 1 and 2 will be described. As shown, in the reach cylinder 4, the cylinder body
A piston 12 slidably fitted in 11 and a piston rod 5 are assembled so as to be movable by a predetermined amount in the axial direction. That is, the piston 12 has a plug 13 at one end.
Has a circular cylindrical hole 12a closed by
Large diameter head formed inside one end of piston rod 5
5a is slidably fitted in close contact. The piston rod 5 penetrates the piston 12 and also penetrates the cylinder head 14 and the head cover 15 which also function as stoppers for the stroke end fitted on the head side (rod side) of the cylinder body 11 to the outside. It has been extended.

Then, the buffer spring 16 is provided in the cylindrical hole 12a of the piston 12.
(Specifically, a compression coil spring) is housed. The buffer spring 16 is interposed between the jaw of the head 5a of the piston rod 5 and the bottom of the cylindrical hole 12a of the piston 12 so that the head 5a
Is pressed toward the plug 13 side.

That is, the piston rod 5 is always held with the position pressed against the plug 13 by receiving the pressing force in the retracting direction by the buffer spring 16 as the initial position, but the pulling force that exceeds the pressing force of the buffer spring 16. When receiving, it moves relative to the piston 12 while compressing the buffer spring 16,
In other words, it is designed to be withdrawn. The head 5a of the piston rod 5 is provided with an oil flow hole 17 which communicates between the plug side of the cylindrical hole 12a and the spring accommodating side.
An oil flow hole 18 is provided through the bottom of the cylinder hole 12a so as to connect the spring housing side of the cylinder hole 12a and the rod side oil chamber of the cylinder body 11. Although not shown, as the oil control valve for controlling the operation of the reach cylinder 4, a type in which the rod side oil chamber port 11a is connected to the tank at the neutral position is used.

This embodiment is constructed as described above. Therefore, in a normal state where no tensile force is applied to the piston rod 5, the piston rod 5 has a buffer spring as shown in FIG.
While the head 5a is pressed against the plug 13 of the piston 12 by the 16, the telescopic operation is performed integrally with the piston 12.

On the other hand, when the large container C is suspended, the piston rod 5 of the reach cylinder 4 is pulled out to the stroke end where the piston 12 contacts the cylinder head 14 as shown in FIG. Accordingly, when the rail 2 is bent as shown in FIG. 9 and the rail 2 is about to be pulled out, the piston rod 5 receives a tensile force as shown by an arrow in FIG. While being compressed, the buffer spring 16 is pulled out beyond the specified stroke end. That is, the piston rod 5 of the reach cylinder 4 absorbs the tensile force by being pulled out according to the magnitude of the tensile force when the tensile force accompanying the bending of the rail 2 is applied, and thus the reach cylinder 4 and its mounting member. The brackets 6 and 9 are protected from excessive load.

When the piston rod 5 is pulled out, as the head 5a moves, oil on the spring housing side and oil from the tank flow into the plug side of the cylindrical hole 12a through the flow holes 17 and 18. Further, the piston rod 5 is returned to the initial position by the restoring force of the buffer spring 16 when the reach cylinder 4 is operated toward the contraction side.

Example 2 Next, Example 2 will be described with reference to FIGS. 3 and 4. In the second embodiment, instead of the circulation hole 18 formed in the piston 12 in the first embodiment, a plug 13 of the piston 12 is provided with a flowing oil hole 19 that communicates the bottom side oil chamber with the cylindrical hole 12a of the piston 12. On the other hand, as the buffer spring 16, a spring slightly stronger than the cylinder thrust is used. Therefore, the normal expansion and contraction operation is similar to that of the first embodiment, as shown in FIG.
Is performed with the head 5a of the piston rod 5 being pressed against the plug 13 of the piston 12.

On the other hand, when the container rod is suspended and a tensile force that exceeds the pressing force of the buffer spring 16 acts on the piston rod 5 due to the bending of the rail 2, the piston rod 5 causes the buffer spring 16 to move.
The tensile force is absorbed by being drawn out while compressing, and at this time, the oil in the spring accommodation side space and the oil in the bottom side oil chamber of the cylinder body 11 flows in the plug side space of the cylinder hole 12a of the piston 12. It flows in through holes 17 and 19. Therefore, in the case of the second embodiment, an oil control valve having an oil passage that connects the bottom side oil chamber port (not shown) of the cylinder body to the tank at the neutral position is used as the oil control valve.

<Embodiment 3> Next, in Embodiment 3 shown in FIG. 5, the piston 12 and the piston rod 5 are integrated, and a buffer spring 16 is interposed between the piston 12 and the cylinder head 14. That is, in the third embodiment, the piston 12 contacts the cylinder head 14 as a stopper via the buffer spring 16, and the spring force of the buffer spring 16 in this case is the same as that in the second embodiment. Is set to be slightly stronger than the thrust of the reach cylinder 4.

Therefore, in the extension operation of the reach cylinder 4 by the normal hydraulic pressure, the position held by the buffer spring 16 becomes the stroke end, but when the container C is hung, a pulling force that exceeds the cylinder thrust force is applied to the piston rod 5. When actuated, the piston rod 5 absorbs the tensile force by compressing the buffer spring 16 and being pulled out beyond the specified stroke end. At this time, the oil in the rod-side oil chamber of the cylinder body 11 flows into the bottom-side oil chamber from the circulation hole 20 provided in the piston 12 through the gap between the outer circumference of the piston and the inner circumferential surface of the cylinder body. The third embodiment is effective in simplifying the structure as compared with the previous two examples.

<Embodiment 4 and Embodiment 5> In Embodiment 4 shown in FIG. 6 and Embodiment 5 shown in FIG. 7, the piston rod 5 has a double structure and the buffer spring 16 is built in the piston rod 5. It was done in this way. That is, in the case of the fourth embodiment, the piston rod 5 is divided into two parts in the axial direction, especially at the tip end side, and the rail-side small-diameter rod is inserted into the cylindrical hole 21a formed at the tip end of the piston-side large-diameter rod 21. 22 formed head 2
2a is slidably fitted. A buffer spring 16 is housed in the cylindrical hole 21a so as to press the head 22a toward the bottom of the cylindrical hole 21a, and the buffer spring 16 is provided by a rod guide 23 fitted to the opening side of the cylindrical hole 21a. Has been received.

On the other hand, in the case of the fifth embodiment, the spindle rod 5 is a large-diameter cylindrical rod 24 and a small-diameter rod inserted into the cylindrical rod 24.
25, and the buffer spring 16 is housed in a large-diameter cylindrical hole 24a formed at the end of the cylindrical rod 24 on the side where the cylindrical rod 24 is connected to the piston 12. The head 25a of the sliding small-diameter rod 25 is pressed toward the plug 26 fitted so as to close the cylindrical hole 24a.

In the case of the fourth and fifth embodiments configured as described above, the strength of the buffer spring 16 can be set regardless of the cylinder thrust.

In the illustrated embodiment, a compression coil spring is shown as the buffer spring 16, but the buffer spring 16 is not limited to this, and another type of spring such as a disc spring may be used.

(Effect of the Invention) As described in detail above, according to the present invention, when a tension force is applied to the piston rod of the reach cylinder due to the bending of the rail when the container is suspended, the piston rod compresses the buffer spring. However, it is designed to absorb the above tensile force by being pulled out beyond a preset stroke end, which allows the reach cylinder itself and its mounting member, the bracket, to be used when the container is suspended. It is possible to protect from excessive load and improve durability.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIGS. 1 and 2 are sectional views showing the reach cylinder of the embodiment 1, respectively, and FIGS. 3 and 4 are sectional views showing the reach cylinder of the embodiment 2, respectively. FIG. 5 is a sectional view showing a reach cylinder of the third embodiment, FIG. 6 is a sectional view showing a reach cylinder of the fourth embodiment,
FIG. 7 is a sectional view showing a reach cylinder of the fifth embodiment, and FIG.
FIG. 9 is a schematic front view of the spreader, and FIG. 9 is a schematic front view of the spreader showing a bent state of the rail when the container is suspended. 1 ... Rail holder, 2 ... Rail 4 ... Reach cylinder, 5 ... Piston rod 11 ... Cylinder body, 12 ... Piston 16 ... Buffer spring

Claims (1)

[Scope of utility model registration request] 1. A rail slidably inserted in a horizontal rail holder is arranged in parallel with the rail for expanding and contracting the rail, a base end portion is supported on the rail holder side, and a piston rod tip is on the rail side. Reach cylinder connected to the, at the stroke end in the direction of extension of the cylinder, hold the piston rod at the specified stroke end position when the tensile force is not applied to the piston rod, and when the tensile force is applied to the piston rod. , A reach cylinder of a telescopic spreader equipped with a buffer spring that allows the piston rod to be pulled out beyond a specified stroke end according to the magnitude of the pulling force.