JPH10139392A - Jst device of fork lift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a rod guide part of the upper end of a cylinder tube by connecting an output rod of a lift cylinder and a bracket fixed to an inner mast to each other in such a manner as to float in the diametral direction of the output rod. SOLUTION: A rod 14 is guided and supported in such a manner as to be elevated through a rod guide mounted on the upper end of a cylinder tube 20 and a seal member 26, and the upper end face of the rod 14 is formed like a projecting spherical surface. The lower surface 15a of a bracket 15 integrally fixed to the upper end part of an inner mast 3 is also formed like a recessed spherical surface. Accordingly, the rod 14 and the bracket 15 are brought into spherical contact with each other. Thus, bending and torsion of the inner mast 3 caused by cargo handling work can be absorbed by the spherical contact part between the rod 14 and the bracket 15, so that excessive force is not applied to the rod 14 so as to improve the durability of the rod guide 25 and the seal member 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mast device for a forklift truck, and more particularly to a mast device in which an outer mast and a cylinder tube of a lift cylinder are integrally formed in advance. It relates to the structure of the connecting portion.

[0002]

2. Description of the Related Art A mast device in which an outer mast and a cylinder tube of a lift cylinder are integrally formed as disclosed in JP-A-57-175699 for the purpose of reducing the number and weight of mast components. It has been known. This type of mast apparatus has a structure in which an output rod of a lift cylinder and a bracket on the inner mast side are rigidly connected.

[0003]

When the output rod of the lift cylinder and the bracket on the inner mast side are rigidly connected to each other as described above, the displacement of the inner mast, such as bending or torsion, during the loading / unloading operation is reduced by the output of the lift cylinder. Due to the direct application to the rod, the load on the rod guide portion, especially at the upper end of the cylinder tube, becomes extremely large. As a result, the durability of the rod guide portion is poor, and particularly, the sealing performance of the rod guide portion is easily deteriorated early. Therefore, it is necessary to frequently perform maintenance and inspection of the seal portion and replacement of the seal member.

The present invention has been made in view of the above-mentioned problems, and the connecting portion between the output rod of the lift cylinder and the inner mast has a certain degree of freedom. It is an object of the present invention to provide a structure for improving the durability of the rod guide portion.

[0005]

According to the first aspect of the present invention, an outer mast and a cylinder tube of a lift cylinder are previously formed integrally with each other, and an inner mast driven up and down by the expansion and contraction operation of the lift cylinder is guided and supported by the outer mast. A mast device having a structure in which the output rod of the lift cylinder and a bracket fixed to an inner mast are connected so as to be able to float in the diameter direction of the output rod.

A second aspect of the present invention is characterized in that the upper end surface of the output rod and the lower surface of the bracket in the first aspect of the invention are formed as spherical or point contact.

According to a third aspect of the present invention, the output rod and the bracket according to the second aspect of the present invention are connected to each other by a connecting body which allows a predetermined amount of play in the vertical direction. I have.

Therefore, according to the first aspect of the present invention,
At the connection between the output rod of the lift cylinder and the bracket of the inner mast, relative movement in the diameter direction of the output rod is allowed, and as a result, displacement such as bending or torsion of the inner mast during cargo handling is absorbed by the connection. Therefore, it is difficult to directly transmit to the output rod side.

In particular, when the two are in spherical contact or point contact as in the second aspect of the invention, the relative movement between the two is smoothly performed, and the relative displacement in the vertical direction is also allowed at the same time.

According to the third aspect of the invention, the relative movement between the output rod and the bracket as described above is allowed, and the inner mast is lowered by the contraction operation of the lift cylinder. Even if the inner mast is caught, only the output rod will not fall down first.

[0011]

According to the first aspect of the present invention, the connecting portion between the output rod of the lift cylinder and the bracket of the inner mast has a floating structure, and the relative movement of the output rod in the diameter direction is allowed. Therefore, the displacement of the inner mast, such as bending and torsion, is absorbed by the floating portion, so that it is difficult for the inner mast to be transmitted to the output rod as an excessive force. Thus, the load on the rod guide at the upper end of the cylinder tube of the lift cylinder can be reduced, and the durability of the rod guide including the seal member and the like can be improved.

In particular, since the floating portion is formed as a spherical contact or a point contact as in the second aspect of the present invention, there is an advantage that the floating operation can be performed more smoothly.

According to the third aspect of the present invention, the output rod and the inner mast bracket are connected to each other by a connecting body having a play in the vertical direction. In addition to the same effect, even if the inner mast is caught in the middle of the lowering of the inner mast, the output rod of the lift cylinder does not descend first, and always moves integrally, thereby improving safety and reliability. There are advantages that can be.

[0014]

1 to 3 show a typical embodiment of the present invention, and show an example of a two-stage mast.

[0015] As shown in FIGS.
Inner mast 3 inside the left and right outer masts 2
Are arranged so as to be able to move up and down. Left and right outer mast 2,
The two inner masts 3 are mutually connected via an upper beam 4, a cross beam 5 and a mast support 6, while the left and right inner masts 3 are mutually connected via a mast head 7 and a tie beam 8. A lift bracket 9 is provided inside each inner mast 3 so as to be able to move up and down, and a finger bar (carriage) 10 is fixed to the lift bracket 9. A fork (not shown) is attached to the finger bar 10. Be attached.

A pair of chain wheels 12 is supported on the mast head 7 via a chain wheel bracket 11, and a lift chain 13 is wound around each chain wheel 12. Each lift chain 13
Is connected to the cross beam 5 and the other end is connected to the lift bracket 9.

As will be described later, since the rod 14, which is the output rod of the lift cylinder 1, is connected to the inner mast 3 via the bracket 15, when the lift cylinder 1 extends from the state shown in FIG. As a result of the lifting operation of the lifting cylinder 3, the chain wheel 12 is raised integrally, and as a result, the finger bar 10 is raised along the inner mast 3 at twice the speed of the lift cylinder 1. In FIG. 2, reference numeral 16 denotes a tilt bracket, and 17 denotes a mast support bracket.

The left and right outer masts 2 described above are similar to those shown in FIG.
As shown in FIG. 5, although the web 18 and the flange portion 19 bent back and forth are formed in a substantially U-shaped cross section, a circle which is a main element of the lift cylinder 1 is provided at an intermediate portion of the web 18. An annular cylinder tube 20 is integrally formed in advance, and the center of the cylinder tube 20 and the center of the web 18 are aligned.

On the other hand, the left and right inner masts 3 disposed inside the left and right outer masts 2 are formed in a substantially H-shaped cross section by the web 21 and the front and rear flange portions 22. When one end of the portion 22 enters the inside of the flange portion 19 on the outer mast 2 side, the inner mast 3 is guided so as to be able to move up and down with respect to the outer mast 2.

That is, the dimensions of the outer mast 2 and the cylinder tube 20 integral therewith overlap each other in the vehicle width direction, and at the same time, the dimensions of the cylinder tube 20 and the inner mast 3 also overlap each other in the vehicle width direction. Since the outer mast 2 and the lift cylinder 1 and the inner mast 3 partially overlap each other in the vehicle width direction as a result, the width dimension W of the left and right masts is reduced.

An inner corner formed by the web 18 of the outer mast 2 and the front and rear flanges 19 is set as an inner angled slide guide surface 23 for the inner mast 3. Inner mast 3 through angled liner 24
The side flange portion 22 is guided so as to be able to move up and down, and the position of the inner mast 3 with respect to the outer mast 2 in the vehicle width direction and the vehicle front-rear direction is regulated. This allows
The left and right masts are formed in a front-rear symmetric shape with respect to a plane passing through the axis of the left and right lift cylinders 1 and 1 as a center of symmetry in plan view.

FIG. 4 shows the rod 14 of the lift cylinder 1.
FIG. 1 is a view showing details of a connecting portion between the inner mast 3 and FIG.
As shown in FIG. 4, the rod 14 includes a rod guide 25 and a seal member 26 mounted on the upper end of the cylinder tube 20.
Is supported so as to be able to ascend and descend via the rod 1
4 has an upper end surface 14a formed in a convex spherical shape. On the other hand, the lower surface 15a of the bracket 15 integrally fixed to the upper end of the inner mast 3 is also formed in a concave spherical shape, whereby the rod 14 and the bracket 15 are in contact with each other by spherical contact.

A substantially L-shaped hook 27 is connected to the upper end of the rod 14 as a connecting body. The tip 27a of the hook 27 extends to the upper surface of the bracket 15 and is slightly smaller than the upper surface. while keeping the play C ₁ are to face each other. The hook 27 is fixed to the rod 14 by a peripheral groove 28 formed on the outer periphery of the upper end of the rod 14, a fixing band 29 and bolts / nuts 30 and 31 fitted into the peripheral groove 28.

As described above, in the connection portion between the rod 14 and the bracket 15 on the inner mast 3 side, since the upper end surface 14a on the rod 14 side and the lower surface 15a on the bracket 15 side are in spherical contact, both can float within the spherical surface. together has become, is relatively movable in the vertical direction within the range of the play C _1.

Therefore, according to the present embodiment, the rod 14 and the bracket 15 on the inner mast 3 are in spherical contact as described above due to the weight of the inner mast 3 itself, and the rod 14 of the lift cylinder 1 is used during the cargo handling operation. Rises, the inner mast 3 is pushed up accordingly.

At this time, the inner mast 3 is
Even if bending or torsion occurs, the displacement is absorbed by the sliding at the spherical contact portion, so that no excessive force is applied to the rod guide 25.

When the rod 14 of the lift cylinder 1 is lowered, the inner mast 3 also loses its weight due to its own weight.
Descends following the movement of. If the inner mast 3 does not follow the movement of the lift cylinder 1 due to being caught or the like during the descent, the tip 27a of the hook 27 comes into contact with the upper surface of the bracket 15 to lower the inner mast 3. Thereby, when the inner mast 3 is caught, it is possible to prevent the rod 14 alone from lowering alone.

As described above, according to the present embodiment, since the bending and twisting of the inner mast 3 during the cargo handling operation can be absorbed by the spherical contact portion between the rod 14 and the bracket 15, an excessive force is applied to the rod guide 25. Therefore, the durability of the rod guide 25 and the seal member 26 is improved.

Here, when the upper end surface 14a of the rod 14 is formed in a spherical shape as described above, while the lower surface 15a of the bracket 15 is formed in a flat shape without being formed in a spherical shape, both are formed as a point. In the form of contact, the same function as in the first embodiment can also be exhibited.

FIG. 5 shows a second embodiment of the present invention.
In this example, instead of the hook 27 shown in FIG.
The fixing band 29 and the bracket 15 are
And are concatenated.

FIG. 6 shows a third embodiment of the present invention.
In this example, the upper end surface 14a of the rod 14 and the bracket 15
Surface 15a of the bracket 15
Bolt 34 penetrating through connection hole 33 formed in
The rod 14 and the bracket 15 are connected with each other.

That is, the stopper bolt 34 is
4 have been screwed to the upper end surface 14a of, while the diameter of the stopper bolt 34 has a play C ₂ be formed smaller than the diameter of the coupling hole 33, having a diameter larger than the connecting hole 33 stopper also between the head portion 34a and the bracket 15 of the bolt 34 are imparted play C _3.

Also in the case of the present embodiment, it is possible to float within the range of the play C ₂ and C ₃ , and it functions exactly the same as the first embodiment.

[Brief description of the drawings]

FIG. 1 is a sectional explanatory view of a mast device showing a typical embodiment of the present invention.

FIG. 2 is a perspective view of a mast device showing a typical embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an exploded perspective view of a main part of FIG. 2;

FIG. 5 is an exploded perspective view of a main part showing a second embodiment of the present invention.

FIG. 6 is an essential part cross-sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lift cylinder 2 ... Outer mast 3 ... Inner mast 14 ... Rod 14a ... Upper end surface 15 ... Bracket 15a ... Lower surface 20 ... Cylinder tube 27 ... Hook (connecting body) 32 ... Wire (connecting body) 34 ... Stopper bolt (connecting body)

Claims (3)

[Claims] 1. A mast device having a structure in which an outer mast and a cylinder tube of a lift cylinder are integrally formed in advance, and an inner mast driven up and down by expansion and contraction of a lift cylinder is guided and supported by the outer mast. A mast device for a forklift truck, wherein the output rod and the bracket fixed to the inner mast are connected so as to be able to float in the diameter direction of the output rod. 2. The mast device for a forklift truck according to claim 1, wherein an upper end surface of the output rod and a lower surface of the bracket are in spherical contact or point contact. 3. The mast device for a forklift truck according to claim 2, wherein the output rod and the bracket are connected to each other by a connecting member that allows a predetermined amount of play in a vertical direction.