JPH10152299A - Forklift truck mast device - Google Patents

Abstract

(57) [Summary] [Problem] If a chain wheel and a lift chain project inside an inner mast, they obstruct an operator's front view. SOLUTION: An outer mast 2 and a cylinder tube 11 of a lift cylinder 1 are integrated so as to overlap each other in the vehicle width direction, and the cylinder tube 1
1 and the inner mast 3 overlap each other in the vehicle width direction. A chain wheel 10 for a lift chain 12 attached to the inner mast 3 is mounted on the outer surface of the upper end of the inner mast 3, and the cylinder tube 1 is mounted in the vehicle width direction.
Overlap with 1.

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 for a forklift truck, in which a relative positional relationship among an outer mast, an inner mast, a lift cylinder, and a chain wheel is changed so that a wider field of view for an operator can be secured. Mast device.

[0002]

2. Description of the Related Art Japanese Unexamined Utility Model Publication No. Sho 59-123096 and Japanese Unexamined Utility Model Publication No. Sho 62-132099 have disclosed so-called wide-view masts having improved visibility in the forward direction of an operator.

In order to reduce the number and weight of components of a mast device, Japanese Patent Application Laid-Open No.
There is one described in Japanese Patent No. 75699.

[0004]

In the former mast device, a pair of left and right lift cylinders for raising and lowering the inner mast are arranged behind the left and right outer masts, and also for raising and lowering the finger bar (carriage) alone. A pair of left and right free lift cylinders are arranged behind the left and right inner masts. Compared to a type in which a single relatively large free lift cylinder is arranged in the middle of the left and right masts, the center of the mast device is Although there is nothing obstructing the field of view, the forward visibility of the operator from the driver's seat is improved, but there is naturally a limit to reducing the width of the mast itself in the vehicle width direction. There is room.

In the latter mast device, the left and right outer masts and the cylinder tubes of the left and right lift cylinders respectively corresponding thereto are integrally formed in advance. In this type, a hollow cylinder is provided on the outer surface of the outer mast. There is a problem in that the tube-equivalent portion is merely integrated in advance so as to circumscribe, and the above-described width dimension cannot be reduced.

In addition, since the chain wheels attached to the inner mast and the lift chains protrude inside the inner mast, these chain wheels and the lift chains undesirably impede the forward view.

The present invention has been made in view of the above problems, and is based on the premise that the outer mast and the cylinder tube of the lift cylinder are integrally formed in advance, and the width of each of the left and right masts. It is an object of the present invention to provide a structure that realizes a wider field of view by reducing the size while preventing a chain wheel or a chain from obstructing a front view.

[0008]

The outer masts and the lift cylinders corresponding to the outer masts and the lift cylinders respectively corresponding to the outer masts overlap each other in the vehicle width direction. Tubes are integrally formed, and the inner mast driven up and down by the lift cylinder is guided and supported by each outer mast so that each of the cylinder tubes and the left and right inner masts overlap each other in the vehicle width direction, At the lowest position of the inner mast, the upper end of the inner mast is set to protrude above the upper surface of the outer mast, and the outer surface of the upper end of the inner mast has the cylinder tube and the chain in plan view. The chain wheel is extended through an axis extending in the vehicle width direction so that the wheel and the wheel overlap each other in the vehicle width direction. It is characterized in that mounted Te.

A second aspect of the present invention is characterized in that the inner mast of the first aspect of the invention is slidably guided and supported on the outer mast via a liner.

According to a third aspect of the present invention, the cylinder tube of the lift cylinder is set so as to be positioned at an intermediate portion of the length of the outer mast in the front-rear direction in the first or second aspect of the invention. The mast has a slide guide surface before and after the cylinder tube of the lift cylinder, and the inner mast is guided and supported by the two slide guide surfaces at the front and rear.

The invention according to claim 4 is characterized in that the entire mast is formed as a two-stage mast by the outer mast and the inner mast according to any one of claims 1 to 3.

According to a fifth aspect of the present invention, the inner mast according to any one of the first to third aspects is a middle mast, and the inner mast is guided and supported inside the middle mast. The whole is formed as a three-stage mast.

Therefore, in the first, fourth, and fifth aspects of the invention, the outer mast, the cylinder tube of the lift cylinder integrated with the outer mast, and the inner mast overlap each other in the vehicle width direction. in addition,
The chain wheel mounted on the outer surface of the upper end of the inner mast also overlaps with the cylinder tube, reducing the size of the left and right masts in the width direction of the vehicle, as well as wrapping around the chain wheel The lift chains do not protrude inward from the left and right masts.

By providing a liner between the outer mast and the inner mast as in the second aspect of the invention, the overlap between the outer mast and the inner mast can be further increased as compared with the roller mast type. Can be enlarged.

According to the third aspect of the present invention, since the inner mast is guided by two slide guide surfaces set before and after the cylinder tube among the outer masts, the inner mast with respect to the outer mast is provided. Lifting and lowering operation is performed smoothly.

[0016]

According to the first, fourth, and fifth aspects of the present invention,
In addition to the left and right outer mast, inner mast and lift cylinder overlapping each other in the vehicle width direction, the chain wheel for the lift chain also overlaps with the cylinder tube, resulting in left and right The size of each mast in the vehicle width direction can be greatly reduced, and the area that obstructs the operator's front view is reduced accordingly, so that the operator's front view can be secured more widely. In addition to improving the workability of cargo handling work, the chain wheel and the lift chain do not obstruct the view because the chain wheel is mounted on the outer surface of the upper end of the inner mast, and this also There is an effect that the operator can secure a wider field of view in front of the operator.

Further, as described above, not only is the outer mast and the cylinder tube of the lift cylinder completely formed integrally, but also the upper end of the inner mast projects above the outer mast at the lowest position of the inner mast. With such a configuration, the outer mast can be substantially shorter than the inner mast, and the weight of the mast device can be further reduced.

In particular, according to the second aspect of the present invention, the inner mast is guided and supported via the liner with respect to the outer mast. The width of the left and right masts can be further reduced by increasing the amount of overlap between the outer mast and the inner mast as compared with that of the first embodiment.

According to the third aspect of the present invention, the cylinder tube is positioned at an intermediate portion of the length of the outer mast in the front-rear direction, and the slide is set in front and rear of the outer mast by sandwiching the cylinder tube of the lift cylinder. Since the guide surface guides the inner mast, in addition to the same effect of the first or second aspect of the present invention, there is an effect that the inner mast can be moved up and down more smoothly.

[0020]

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

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 connected to each other in parallel via a tie beam 5 while the inner masts 3 are connected to each other in parallel via an upper beam 4 and a cross beam (not shown). A lift bracket 6 is provided inside each inner mast 3 so as to be able to move up and down, and a finger bar (carriage) 7 is fixed to the lift bracket 6. A fork (not shown) is attached to the finger bar 7. Be attached.

Also, as shown in FIGS. 1 and 3, even when the inner mast 3 is at the lowest position, the upper end of the inner mast 3 projects from the upper end surface of the outer mast 2 by a predetermined amount a so as to have a step. The length of both masts 2 and 3 is set.

A chain wheel bracket 8 is welded and fixed to the outer surface of the upper end of each inner mast 3, and a chain wheel 10 can be rotated on the chain wheel bracket 8 via a horizontal shaft 9 extending in the vehicle width direction. It is attached to. The chain wheel 10 mutually overlaps with the cylinder tube 11 of the lift cylinder 1 in the vehicle width direction in plan view as described later. The above-mentioned chain wheel 10 includes a lift chain 1
2, one end of the lift chain 12 is connected to the outer mast 2 via a chain anchor bracket 13, and the other end is also connected to the finger bar 7 via a chain anchor bracket 14.

Since the piston rod 15 of the lift cylinder 1 is connected to the chain wheel bracket 8 as shown in FIGS. 1 and 3, when the lift cylinder 1 extends from the state shown in FIGS. 3
As a result, the chain wheel 10 integrally rotates while rotating, and as a result, the finger bar 7 rises along the inner mast 3 at a speed that is twice the extension speed of the lift cylinder 1. It should be noted that the piston rod 15 of the lift cylinder 1 and the chain wheel bracket 8 do not necessarily need to be rigidly connected, and the distal end surface of the piston rod 15 abuts the chain wheel bracket 8 at least in the state shown in FIGS. Just do it.

The left and right outer masts 2 are formed in a substantially U-shaped cross-section by a web 16 and a flange portion 17 formed by bending the front and rear portions thereof as shown in FIGS. An annular cylinder tube 11, which is a main element of the lift cylinder 1, is formed integrally in the middle of the web 16 in advance, and the center of the cylinder tube 11 matches the center of the web 16.

On the other hand, the left and right inner masts 3 disposed inside the left and right outer masts 2 are formed as a substantially I-shaped or H-shaped cross-section by the web 18 and the flange portions 19 at the front and rear thereof. Its inner mast 3
The inner mast 3 is guided so as to be able to move up and down with respect to the outer mast 2 by having one end of the flange portion 19 enter the inside of the flange portion 17 on the outer mast 2 side.

That is, the outer mast 2 and the cylinder tube 11 integral therewith have dimensions overlapping each other in the vehicle width direction, and at the same time, the cylinder tube 11 and the inner mast 3 also have dimensions mutually overlapping in the vehicle width direction. In addition to overlapping, FIG.
The chain wheel 10 also overlaps with the cylinder tube 11 in the vehicle width direction as shown in FIG.
As a result, the outer mast 2, the lift cylinder 1, the inner mast 3, and the chain wheel 10 partially overlap each other in the vehicle width direction, thereby reducing the width dimension W of the left and right masts.

An inner corner formed by the web 16 of the outer mast 2 and the front and rear flanges 17 is set as an inner angled slide guide surface with respect to the inner mast 3, and the inner angled slide guide surface is similarly formed with respect to this slide guide surface. The inner mast 3 side flange portion 22 is guided so as to be able to ascend and descend through the liner 20 of the inner mast 3, 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.

Therefore, according to the present embodiment, the size of the left and right masts including the outer mast 2, the inner mast 3, the lift cylinder 1 and the chain wheel 10 in the vehicle width direction is reduced, so that the operator as viewed from the driver's seat is reduced. The area obstructing the field of view of the operator can be made as small as possible, whereby the forward field of view of the operator can be secured more widely, and workability and safety during cargo handling can be improved.

In particular, since the chain wheel 10 is located above the outer mast 2 integral with the cylinder tube 11 and on the outer side of the inner mast 3, the chain wheel 1 and the lift chain 12 can be viewed from the operator's front view. Without hindrance, this can further widen the field of view of the operator. In addition, as shown in FIGS. 1 and 3, even when the inner mast 3 is at the lowest position, the inner mast 3 can communicate with the outer mast 2. Since there is a step a between the outer mast 2 and the inner mast 3, the length can be substantially reduced by the step a.

FIG. 4 is a view showing a second embodiment of the present invention, and shows an example of a three-stage mast having a free lift function.

In this embodiment, the relative positions of the outer mast 2, the lift cylinder 1, the middle mast 21 and the chain wheel 10 are basically the same as those shown in FIG. An inner mast 22 having the same shape as the middle mast 21 is guided and supported via a liner 23. One end of the lift chain 12 wound around the chain wheel 10 is connected to the inner mast 22 via a chain anchor bracket 24 and a connection plate 25.

On the other hand, a free lift cylinder 26 is provided upright on the lower beam 25 connecting the left and right inner masts 22, 22 to each other. This free lift cylinder 2
A chain wheel 27 is obliquely attached to the tip of the piston rod of No. 6, and one end of a free lift chain 28 wound around the chain wheel 27 is connected to the inner mast 22 or the cylinder tube 29 of the free lift cylinder 26. And the other end is connected to the lift bracket 3 via the chain anchor bracket 30.
Connected to 1.

Therefore, if the free lift cylinder 26 is extended, the lift bracket 31 can be independently raised with respect to the inner mast 22 within the stroke range of the free lift cylinder 26, and the lift cylinder 1 can be further extended. If this is done, the inner mast 22 will rise together with the lift bracket 31 at twice the speed of the middle mast 21 as the middle mast 21 and the chain wheel 10 rise.

In this embodiment, since the outer mast 2, the middle mast 21, the lift cylinder 1, and the chain wheel 10 overlap each other in the vehicle width direction, they are exactly the same as in the first embodiment. Function and effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a mast device according to a first embodiment of the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a view in the direction of arrow A in FIG. 2;

FIG. 4 is a plan view of a mast device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lift cylinder 2 ... Outer mast (outside mast) 3 ... Inner mast (inner mast) 6 ... Lift bracket 8 ... Chain wheel bracket 9 ... Shaft 10 ... Chain wheel 11 ... Cylinder tube 12 ... Lift chain 20 ... Liner 21 ... Middle mast ( Inner mast) 26 ... Free lift cylinder

Claims (5)

[Claims] 1. An outer mast and a corresponding lift cylinder cylinder tube are integrated so that the left and right outer masts and the left and right lift cylinders individually corresponding to the outer masts overlap each other in the vehicle width direction. The inner mast driven up and down by the lift cylinder is guided and supported by each outer mast so that the cylinder tubes and the left and right inner masts overlap each other in the vehicle width direction. At the lowermost position, the upper end of the inner mast is set to protrude above the upper surface of the outer mast, and the outer surface of the upper end of the inner mast is provided with the cylinder tube and the chain wheel in a plan view. The chain wheels are mounted via shafts extending in the vehicle width direction so as to overlap each other in the width direction. And a mast device for a forklift truck. 2. The mast device for a forklift truck according to claim 1, wherein the inner mast is slidably guided and supported on an outer mast via a liner. 3. A cylinder tube of a lift cylinder is set at an intermediate portion of the length of the outer mast in the front-rear direction, and the outer mast slides back and forth between the cylinder tubes of the lift cylinder. The mast device for a forklift truck according to claim 1 or 2, wherein the mast has a surface, and the inner mast is guided and supported by the two front and rear slide guide surfaces. 4. The mast device for a forklift truck according to claim 1, wherein the entire mast is formed as a two-stage mast by the outer mast and the inner mast. 5. The mast according to claim 1, wherein the inner mast is a middle mast, and the inner mast is guided and supported inside the middle mast so that the entire mast is formed as a three-stage mast. 4. A mast device for a forklift truck according to any one of 3.