JPH078717B2 - Forklift mast device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mast device for a forklift, more specifically, a mast device in which an inner mast having a U-shaped cross section is housed in an outer mast having a U-shaped cross section so as to be vertically movable. Regarding

(Prior Art) Conventionally, as the main mast device, a type in which a liner guides up and down movements of an inner mast housed in the outer mast and a type in which a roller guides the inner mast are known. The retractable mast device has a feature that the front view from the driver's seat can be expanded compared to a mast device of a type in which an outer mast and an inner mast are arranged side by side in the vehicle width direction (left and right direction).

The former liner method uses an outer mast as shown in Fig. 11.
A liner is provided between the front and rear inner surfaces of 40 and the front and rear outer surfaces of the inner mast 41 housed in the outer mast 40.
In addition to interposing 42, a side liner 43 is interposed between the inner surface of the outer mast 40 and the outer surface of the inner mast 41, and the liner 42, 43 receives the front-rear and left-right moments acting on the inner mast 41. It is like this. The lift roller 45 attached to the lift bracket 44 rolls in the U-shaped space of the inner mast 41.

The latter roller system is, for example, Japanese Patent Publication No.
49548 or Japanese Utility Model Laid-Open No. 54-159575 is known. The roller system of both of these publications is shown in FIGS.
The configuration is shown in Fig. 14.

That is, at the upper end of the outer mast 40, two front and rear outer mast rollers that roll on the front and rear outer surfaces of the inner mast 41 are used.
While 46 and 47 are attached via the roller bracket 50, two inner and mast rollers 48 and 49, large and small, that roll on the front and rear inner surfaces of the outer mast 40 are attached to the lower end of the inner mast 41.
The mast rollers are attached via a character-shaped roller bracket 51, and a moment in the front-rear direction is received by the mast rollers. The forward moment acting on the inner mast 41 is much larger than the rearward moment, so that the inner mast roller 49 on the rear side has a large diameter. Further, as shown in FIG. 12, the lateral moment of the left-right direction is received by the side surface of the rear inner mast roller 49 having a large diameter coming into contact with the thick portion formed in the inner surface corner of the outer mast side portion. . The lift roller 45 attached to the lift bracket 44 is housed so as to roll in the U-shaped space of the inner mast 41.

(Problems to be Solved by the Invention) However, in the former liner type mast device described above, there is a problem that the sliding resistance of the mast is large, which adversely affects the ascending speed, resulting in poor efficiency.
Wears severely and requires frequent liner replacement,
Moreover, since the replacement work is troublesome, there is a problem that the maintenance cost is high.

On the other hand, in the case of the latter roller system, since the inner mast rollers 48 and 49 are arranged just below the inner mast 41, the lower lift roller 45 is located at the rear side with the lift bracket 44 positioned at the lower end. It is necessary to dispose the inner mast roller 49 at a position above the inner mast roller 49 by the dimension D shown in FIG. In particular, since the roller pin 49a of the inner mast roller 49 has a cantilever structure with respect to the L-shaped roller bracket 51 as shown in the figure, it is necessary to thicken the roller pin 49a to secure the strength. Inevitably, the roller diameter will be increased. For this reason, the lift roller 45 of the lift bracket 44 must be disposed at a position considerably higher than the lower end of the roller bracket 51, which is substantially the lower end of the inner mast 41, and as a result, the total height H of the mast becomes high. In some cases, it cannot be used for cargo handling work inside a room with a low ceiling.

Therefore, in view of the above problems, it is an object of the present invention to provide a mast device improved by adopting a roller system and suppressing the total height of the mast as low as possible.

(Problems to be Solved by the Invention) The present invention is configured as follows to solve the above problems.

In a mast device arranged to store an inner mast with a U-shaped cross section in an outer mast with a U-shaped cross section, an outer mast roller that rollably abuts the front outer surface of the inner mast at the upper end of the outer mast, and slides on the rear outer surface of the inner mast. A rear liner that movably abuts is attached.

On the other hand, at the lower end of the inner mast, an inner mast roller that rollably abuts on the rear inner surface of the outer mast and a front liner that slidably abuts the front inner surface of the outer mast are attached.

A roller bracket for supporting both ends of the roller pin of the inner mast roller is provided at a corner of the rear lower end of the inner mast, and the roller bracket is a lift for a lift bracket that rolls in a U-shaped space of the inner mast. It is formed in a substantially triangular shape with the inclined surface facing the roller.

(Operation) With the configuration described above, in the mast device of the present invention, the outer mast roller and the inner mast roller receive a large positive moment acting on the inner mast during normal cargo handling work, and the empty load The rear liner and the front liner receive a relatively small rearward moment that acts when the vehicle is traveling in a car. That is, since the up and down movement of the inner mast during the cargo handling work is guided by the outer mast roller and the inner mast roller, the up and down movement becomes smooth with small sliding resistance.

Further, since the roller pin of the inner mast roller is supported at both ends by the roller bracket, the pin diameter can be reduced to reduce the roller diameter, and the roller bracket is provided on the opposite side of the lift bracket to the lift roller. Since it is formed into a substantially triangular shape with an inclined surface, the rising dimension from the lower end of the inner mast can be kept low.

As a result, the lift roller can be arranged so as to be as close to the lower end of the inner mast as possible when the lift bracket is located at the lower end.

(Example) Hereinafter, the Example of this invention is concretely described based on drawing.

<Example 1> First, Example 1 will be described with reference to Figs.
A pair of left and right outer masts 1 are attached at their lower end portions to the vehicle body side by a mast support 2 so as to be able to rotate forward and backward, and are tilted forward and backward by a tilt cylinder (not shown) connected to a tilt bracket 3 at a substantially intermediate portion. The left and right outer masts 1 are formed in a U-shaped cross section, and the left and right inner masts 4, which are also formed in a U-shaped cross section, are housed in the U-shaped space so as to be vertically movable.

An outer mast roller 5 that rolls on the front outer surface of the inner mast 4 is mounted on the front side of the upper end of the outer mast 1 via a roller bracket 6, and a rear inner surface of the outer mast 1 rolls inside the lower end of the inner mast 4. The inner mast roller 12 is mounted via the roller bracket 13, and the inner mast 4 is attached by these both mast rollers 5 and 12.
It receives a forward (acting with the arrow F in FIG. 2) moment acting on.

As shown in FIG. 4, a roller bracket 6 for the outer mast roller 5 includes a fixing bracket 6a fixed to the front end surface of the outer mast 1 by welding or the like and protruding forward, and a protective bracket 6b connected to the fixing bracket 6a by a bolt 7. It is a combination type with. The outer mast roller 5 is arranged in a storage recess 8 formed in the protective bracket 6b with its front and rear parts exposed, and a radial bearing 10 is provided for a roller pin 9 which is fixedly penetrated by the roller bracket 6. It is rotatably assembled via two thrust bearings 11 on the left and right.

Further, the roller bracket 13 for the inner mast roller 12 is fixed to the corner portion of the rear lower end portion of the inner mast 4 by welding or the like as shown in FIG. 5, and has a substantially U-shaped plan view and a side view. The front surface of the lift bracket 30 facing the lower lift roller 32 is formed in a substantially triangular shape with an inclined surface. The inner mast roller 12 is rotatably attached to the roller pin 15 which penetrates the roller bracket 13 and is supported at both ends in a state of being arranged in the U-shaped space of the roller bracket 13.

Further, a rear liner 19 slidably abutting the rear outer surface of the inner mast 4 is arranged on the rear inner surface of the outer mast upper end portion, while the rear inner surface of the inner mast lower end portion is slidable on the front inner surface of the outer mast 1. A front liner 20 is arranged in contact with the front liner 20. The front and rear liners 19 and 20 receive a rearward (R arrow direction in FIG. 2) moment acting on the inner mast 4. In general, the backward moment that acts on the inner mast 4 is small enough to occur during traveling with an empty load, and therefore the liner 1
Even the support structure with 9,20 is sufficient in strength.

Further, the inner mast 4 is provided on the side of the upper end of the outer mast.
The mast side roller 24 rolling on the outer side surface of the outer mast is arranged, while the side liner 21 sliding on the inner side surface of the outer mast 1 is arranged on the inner side surface of the lower end of the inner mast. The lateral moment acting on the inner mast 4 is received by the 24 and the side liner 21.

Each liner 19, 20, 21 has two upper and lower pins 22 provided on the liner 19, 20, 21 as shown in FIG. 6 or 7.
Is attached by fitting it into a pin hole 23 formed on the mast side. In addition, the mast side roller 24 is the seventh
As shown in the drawing, the outer mast 1 is abutted against the outer surface of the inner mast 4 through an opening penetrating the outer mast 1, and is attached to the outer mast 1 via a bracket 25.

As shown in FIG. 1, a lift cylinder 26 is erected on the rear side of each outer mast 1, and the lower end of the lift cylinder 26 is attached to the outer mast 1 via a bracket (not shown) or the lower cross of the outer mast 1. Beam 1a
The upper end of the piston rod 27 is connected to the upper tie beam 4a of the inner mast 4.

Further, as shown in FIG. 1, the upper tie beam 4a is extended so as to wrap around the outer mast 1, and the chain wheel 28 is attached to the extended portion with the rotation center line thereof in the left-right direction. ing. The lift chain 29 hung on the chain wheel 28 is
A rear end portion that passes through the rear side is connected to a chain support (not shown) that is provided so as to project on the upper outer surface of the outer mast 1, and a front end portion that passes through the front side of the chain wheel 28 moors the fork 33. It is connected to the chain support 31 of. That is, the lift bracket of the lift chain 29
The front side portion connected to 30 is arranged using the projection plane in the front-rear direction with respect to the outer mast 1. The lift bracket 30 is moved up and down via a lift roller 32 that is rollably arranged in the U-shaped space of the inner mast 4.
In FIG. 1, 1b is an upper cross beam of the outer mast 1, and 4b is a lower tie beam of the inner mast 4.

As described above, in the mast device according to the present embodiment, the inner mast 4 which is a front view hindrance member is housed in the outer mast 1, and the lift cylinder 26 is installed in the outer mast 1.
Since the front portion of the lift chain 28 connected to the lift bracket 30 is arranged outside the mast in the front-rear projection plane of the outer mast 1, the obstruction area of the front field of view thereof is shown in FIG. As a result, a narrow range indicated by a diagonal line is formed, and as a result, a wide front view can be obtained.

Further, in a normal cargo handling work mode, a large forward moment indicated by an F arrow in FIG. 2 acting on the inner mast 4 by the weight of the lift bracket 30 and the fork 33 (weight of the load when there is a load) is applied to the inner mast. 4, the outer mast roller 5 rolling on the front outer surface and the inner mast roller rolling on the rear inner surface of the outer mast 1.
Since it is configured to be received by 12 and 12, the inner mast 4 can be smoothly moved up and down with a small sliding resistance.

Thus, in the present embodiment, as described above, the both ends of the roller pin 14 of the inner mast roller 12 are supported by the roller brackets 13, so that the pin diameter can be reduced and the roller diameter can be reduced accordingly. In addition, since the roller bracket 13 itself is formed into a substantially triangular shape with the inclined surface on the front side, the rising dimension from the lower end of the inner mast, that is, the interference range with respect to the lift roller 32 can be suppressed to a low level. As shown, the axial distance L between the inner mast roller 12 and the lift roller 32 when the lift bracket 30 is located at the lower end can be reduced. As a result, it becomes possible to suppress the total height H1 of the mast to be lower than that of the conventional roller type mast device.

<Second Embodiment> A second embodiment will be described with reference to FIG. In this embodiment, a mast side roller 34 is provided on the side surface of the outer mast 1 in place of the side liner 21 in the above-described first embodiment, and other configurations are exactly the same as in the first embodiment. Therefore, in the second embodiment, the lateral moment due to the eccentric load acting on the inner mast 4 during loading is received by the outer mast side mast side roller 24 and the inner mast side mast side roller 34, so that the inner mast 4 is moved up and down. It is effective in reducing the sliding resistance at the time.

<Embodiment 3> In Embodiment 3, as shown in FIG. 10, the sliding surface of the outer mast 1 on which the side liner 21 of the inner mast 4 slides is formed as a convex surface 1c, and such a convex structure is adopted. In this case, there is an advantage that some processing for increasing the surface roughness of the sliding surface is easy.

Although not shown, both the mast side roller 34 of the inner mast 4 described in the second embodiment and the side liner 21 described in the first embodiment are arranged side by side, and the inner mast 4 is in a descending state in which the masts often overlap. Then, the left and right moments are received by the mast side roller 24 of the outer mast 1 and the side liner 21 of the inner mast 4, and when the inner mast 4 having a small mast overlap is raised, the mast side roller 24 of the outer mast 1 and the mast side roller of the inner mast 4 are It is also possible to configure so as to receive a lateral moment with 34 and.

(Effects of the Invention) As described in detail above, according to the present invention, it is of course possible to secure a wide front field of view, which is a characteristic of a mast device in which the inner mast is housed and arranged in the U-shaped space of the outer mast. Since the outer mast roller and the inner mast roller receive a large positive moment acting on the inner mast, the sliding resistance of the mast can be reduced and the inner mast can be smoothly moved up and down.

Moreover, in the present invention, the axial distance between the lift roller and the inner mast roller when the lift bracket is located at the lower end can be reduced as compared with the conventional roller mast device, so that the total height of the mast can be suppressed to that extent. This makes it possible to provide a mast device suitable for cargo handling work indoors with a low ceiling.

[Brief description of drawings]

1 to 8 show a first embodiment of the mast device of the present invention. FIG. 1 is a plan view showing the lower half of the right half by cutting, FIG. 2 and FIG. It is a view as seen from the direction of arrow A, which is shown in FIG. 2 in the relationship between the outer mast and the inner mast, and in FIG. 3 in the relationship between the inner mast and the lift bracket. FIG. 4 is a perspective view showing the outer mast roller mounting structure in an exploded state, FIG. 5 is a perspective view showing the inner mast roller mounting structure in an exploded state, and FIGS. 6 and 7 are liner and side roller mountings. Sectional view showing the structure,
FIG. 8 is an explanatory view showing a visual field obstruction area from the rear of the mast by the mast device. FIG. 9 shows the second embodiment of the present invention.
Fig. 10 is a side view of the mast showing Fig. 10, and Fig. 10 is a partial sectional view showing the third embodiment. Further, FIG. 11 is a plan sectional view showing a conventional liner type mast device, FIG. 12 is a plan sectional view of a conventional roller type mast device, FIG. 13 is a sectional view taken along the line BB of FIG. 12, and FIG. FIG. 3 is a perspective view showing a mounting structure of an inner mast roller in a roller mast device. 1 …… Outer mast 4 …… Inner mast 5 …… Outer mast roller 12 …… Inner mast roller 13 …… Roller bracket 19 …… Rear liner 20 …… Front liner

Claims (1)

[Claims] 1. A mast device arranged to accommodate an inner mast having a U-shaped cross-section in an outer mast having a U-shaped cross-section, the outer mast roller having an outer mast roller abutting rotatably on a front outer surface of the inner mast at an upper end of the outer mast. A rear liner that slidably contacts the outer surface of the inner mast is attached, and an inner mast roller that slidably contacts the inner rear surface of the outer mast at the lower end of the inner mast and a front that slidably contacts the inner inner surface of the outer mast. A liner is attached, and a roller bracket for supporting both ends of the roller pin of the inner mast roller is provided at a corner of a rear lower end of the inner mast, and the roller bracket is a lift for a lift bracket that rolls in a U-shaped space of the inner mast. The fountain is formed in a substantially triangular shape with the inclined surface facing the roller. Mast assembly of Clift.