JP2010030771A - Forklift tilting device and forklift equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forklift tilting device simple in structure for separately operating the tilting of a mast and a fork without reducing an allowable load while reducing the fore-and-aft displacement of a load center, and to provide a forklift equipped therewith. <P>SOLUTION: The forklift tilting device includes a longitudinally tiltable mast 6 erected on the front side of a vehicle body, a lift bracket 9 moved up and down along the mast 6, the fork 4 supported on the lift bracket 9, and a fluid pressure cylinder 14 for tilting the fork 4, the fluid pressure cylinder 14 elongated snf contracted for tilting the fork 4. The lift bracket 9 face-contacts with the back face of the fork. The upper end of the fork is provided with a journal which is journaled to the lift bracket 9 to serve as a supporting point 15 during tilting the fork 4. The fluid pressure cylinder 14 provided on the back face of the fork is elongated to thrust the fork at its back-face lower part and isolate it from the lift bracket 9. Then, the fork is tilted to rise forward around the supporting point 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a tilting device for a forklift having a mast standing in front of a vehicle body and tiltable in the front-rear direction, a lift bracket provided on the mast so as to be movable up and down, and a fork supported by the lift bracket, The present invention relates to a forklift equipped with a device.

  In general, a forklift has a mast instructed by a fork that can be raised and lowered at the front of the vehicle body, and carries a cargo handling work by loading and transporting cargo items on the fork. FIG. 8 shows an outline of a conventional forklift. A forklift 50 shown in FIG. 8A is a counterbalance type forklift, and includes a vehicle body 01 having a pair of left and right front wheels 02 and a pair of left and right rear wheels 03, a fork 04 for loading luggage, and a driving unit. 05. A counterweight 013 is provided behind the operation unit 05.

A mast 06 that can be expanded and contracted in the vertical direction is attached to the front end portion of the vehicle body 01 so as to be tiltable in the front-rear direction, and a tilt cylinder 010 that tilts in the front-rear direction is provided between the vehicle body 01 and the mast 06. The fork 04 is installed on the mast 06 via a lift bracket 09.
As shown in the two-dot broken line in FIG. 8A and FIG. 8B, in the conventional forklift, the fork 04 always tilts when the mast 06 is tilted in the front-rear direction. The load supported by the fork 04 may collapse or fall. Moreover, since the movement of the load center accompanying tilting with the mast is large, the fore-and-aft safety of the forklift is lowered.

In relation to this, a hinged fork as shown in FIGS. 9A and 9B is provided in which only the fork can tilt in the front-rear direction. Since the structure from the mast to the rear of the vehicle body is the same as that shown in FIG. In the hinged fork shown in FIG. 9A, the fork 04 tilts due to the expansion and contraction of the hydraulic cylinder 014 disposed between the lift bracket 09 and the back part of the fork 04. At that time, the fork 04 tilts back and forth with the pin 015 at the center of the fork 04 as a fulcrum. FIG. 9B is an application of the above-described FIG. 9A, in which the lift bracket 09 is divided and configured.
The hinged fork can hold and hold a load by tilting the fork, so that it is possible to accurately carry out a cargo handling work in forestry such as raw wood and square wood and a long object such as a steel pipe. Moreover, since only the fork is tilted, the displacement of the load center in the front-rear direction can be reduced. However, the hinged fork has a front overhang (corresponding to F in FIG. 9) corresponding to the distance from the front wheel axle of the vehicle body to the tip of the fork, which is longer than that of the forklift as shown in FIG. However, it is not suitable for heavy work. Further, since the fork 04 that freely rotates around the pin 15 is fixed by the cylinder 014, there is a risk that the load may fall if the fork 04 is lowered forward due to oil leakage of the cylinder that has been overloaded. It is not suitable for heavy work.

For this reason, Patent Document 1 (Japanese Patent Application Laid-Open No. 5-319798) has been proposed as a tilt-type forklift that can be used for heavy work while shortening the front overhang.
In Patent Document 1, in a tilt-type forklift, a fork is inserted into a fork insertion port such as a pallet in a state where a guide mast is almost upright to support an object to be conveyed. Then, in a state where the object to be conveyed is fixed to a pallet or the like, the small first and second fluid pressure cylinders are operated to incline the fork, and the object to be conveyed is also inclined at the same time. At this time, when the first and second fluid pressure cylinders are driven to advance the rod, the first fluid pressure cylinder pushes the second link, and the second fluid pressure coupled to the second link. The cylinder pushes the lower part of the guide mast and slides it along the guide rail, and the guide mast and the conveyed object are inclined.

On the other hand, as a fork tilting device for a forklift that tilts the fork itself and can be used for heavy work, a technique such as Japanese Patent Application Laid-Open No. 7-228497 has been proposed.
In Patent Document 2, an upright portion of a fork is attached to a movable mast so as to be tiltable, and an operating device for tilting the fork is installed above the upright portion of the fork in the movable mast. A technique for connecting a fork to a fork via a connecting member is shown. A cable or an arm is used as the connecting member, and the fork is tilted backward through the connecting member. Further, the fork can be directly tilted by the hydraulic cylinder without using a connecting member.

JP-A-5-319798 JP 7-228497 A

However, in the above-mentioned Patent Document 1, two links and two fluid pressure cylinders are combined and the lower part of the guide mast is slid to tilt the fork. The second fluid pressure cylinder must be interlocked and is difficult to control. Furthermore, the mast tilt and the fork tilt cannot be operated separately.
In Patent Document 2, the fork itself is tilted to reduce the displacement in the front-rear direction of the load center accompanying the tilting of the fork to increase safety during work. However, a hydraulic cylinder is provided at the top of the fork. Therefore, there is a risk that the fork will fall forward due to the inconvenience of the hydraulic equipment and the load will fall.

  Therefore, in view of the problems of the prior art, the present invention is a forklift that is structurally simple and can operate the mast and fork tilt separately without reducing the allowable load and can reduce the displacement of the load center in the front-rear direction. It is an object to provide a tilt device and a forklift provided with the device.

In order to achieve the above object, the present invention provides a mast that stands in front of a vehicle body and that can tilt in the front-rear direction, a lift bracket that moves up and down along the mast, a fork supported by the lift bracket, and the fork A tilt device for a forklift that tilts the fork by extending and contracting the fluid pressure cylinder,
The lift bracket and the fork back surface are in surface contact with each other, and the fork upper end portion is pivotally attached to the lift bracket and includes a pivot attachment portion serving as a fulcrum for tilting the fork.
The fluid pressure cylinder provided on the back surface of the fork extends and presses the lower part of the back of the fork to be separated from the lift bracket, and the fork is tilted forwardly with the pivoting portion as a fulcrum. .

According to the present invention, since only the fork can be tilted without lengthening the front overhang, the allowable load can be maintained without reducing the longitudinal stability of the forklift.
Further, even if the fluid pressure cylinder breaks down due to, for example, a hydraulic equipment trouble and the fork tilts forward due to the load of the load, the fork is brought into surface contact with the lift bracket, so that the fork position does not fall forward than the horizontal. Therefore, the load does not fall even if there is a problem with the fluid pressure cylinder. Also, there is no change in capability such as allowable load.
Furthermore, the tilt device of the present invention is simple in structure because it is only necessary to provide one or more fluid pressure cylinders on the mast of a conventional forklift. Further, the fork can be lifted forward (backwardly tilted) continuously with only one or a plurality of fluid pressure cylinders.

The mast has a mast standing in front of the vehicle body and tiltable in the front-rear direction, a lift bracket that moves up and down along the mast, a fork supported by the lift bracket, and a fluid pressure cylinder that tilts the fork. In a tilt device for a forklift that tilts the fork by extending and contracting the fluid pressure cylinder,
The lift bracket is divided into a front bracket and a rear bracket, the front bracket and the rear bracket are in surface contact, and the front bracket and the fork are attached and provided,
The upper end of the front bracket is connected to the link arm, the lower end of the front bracket is connected to the rear bracket via the fluid pressure cylinder, and the fork is tilted back and forth by extending and contracting the fluid pressure cylinder. Features.

  As described above, according to the present invention, in addition to the above description, the fork can be moved forward (backward tilt) or forwardly lowered (forward tilt) by extending and contracting the fluid cylinder. Similarly, it is only necessary to provide one or more fluid pressure cylinders on the mast of a conventional forklift, which is structurally simple and can be operated continuously.

Further, the fluid pressure cylinder is extended to tilt the fork forwardly with the link arm as a fulcrum, and the fluid pressure cylinder is contracted to tilt the fork downward with the lower end of the front bracket as a fulcrum. And
As a result, the fork can be tilted forward and backward without projecting the fulcrum forward, so that the working radius can be maintained and safety can be ensured.

Further, the tilting of the fork is performed separately from the tilting of the mast.
Since the mast and the fork can be tilted separately, it is not necessary to tilt the mast after the mast operation. Even when the mast is tilted forward, the fork can be tilted for cargo handling work. Thus, when the load is light, the work radius can be increased, and the cargo handling work can be performed even if there is an obstacle in front of the vehicle body.

Moreover, it is preferable that the forklift of this invention is a forklift provided with the above-mentioned tilt apparatus.
As a result, it is possible to provide a forklift that is structurally simple and can operate the tilting of the mast and the fork separately without reducing the allowable load and can reduce the displacement of the load center in the front-rear direction.

Furthermore, the forklift of the present invention detects the height of the mast, the inclination of the mast, and the load of the load mounted on the fork, and invalidates the command from the control unit provided in the vehicle body to regulate the cargo handling operation. An interlock means is provided.
In this way, the interlock mechanism can automatically stop when trying to do more than the capacity of the forklift, so that the stability of the vehicle body can always be maintained even when the working radius increases. Can be prevented from falling.

As described above, according to the present invention, since only the fork can be tilted without increasing the front overhang, the allowable load can be maintained without reducing the longitudinal stability of the forklift.
Further, even if the fluid pressure cylinder breaks down due to, for example, a hydraulic equipment trouble and the fork tilts forward due to the load of the load, the fork is brought into surface contact with the lift bracket, so that the fork position does not fall forward than the horizontal. Therefore, the load does not fall even if there is a problem with the fluid pressure cylinder. Also, there is no change in capability such as allowable load.
Furthermore, the tilt device of the present invention is simple in structure because it is only necessary to provide one or more fluid pressure cylinders on the mast of a conventional forklift. Further, the fork can be continuously tilted with only one or a plurality of fluid pressure cylinders.
Furthermore, since the fork can be tilted forward and backward without projecting the fulcrum forward, the working radius can be maintained and safety can be ensured.
Further, since the tilting of the mast and the fork can be performed separately, the post-mast tilt during the handling operation becomes unnecessary. On the other hand, even when the mast is tilted forward, the fork can be tilted to perform the cargo handling operation.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Only.
1 is a side view of the forklift according to the first embodiment, FIG. 2 is a side view showing a tilting state of the forklift according to the first embodiment, FIG. 3 is a perspective view showing a tilt device of the forklift according to the second embodiment, and FIG. 5 is a side view showing a tilting state of a forklift according to a second embodiment, FIG. 5 is a diagram for explaining a tilting device for a forklift according to a third embodiment, and FIG. 6 is a side view showing a use state according to the embodiment of the present invention. These are the circuit diagrams of the tilting device which concerns on embodiment of this invention.
In the present invention, a hydraulic cylinder is mainly used as the fluid pressure cylinder, but an air cylinder or other fluid pressure cylinder can be used instead of the hydraulic cylinder.

(Embodiment 1)
FIG. 1 is a side view of a forklift according to an embodiment of the present invention.
In FIG. 1, a forklift 100 includes a vehicle body 1 having a pair of left and right front wheels 2 and a pair of left and right rear wheels 3, a fork 4 for loading a load, and a driving unit 5. The operation unit 5 is provided with an operator seat 12, a handle 17 positioned in front of the operator seat 12, a lift lever, a tilt lever, and the like. A weight 13 is provided.

A mast 6 that can be expanded and contracted in the vertical direction is attached to a front end portion of the vehicle body 1 so as to be tiltable in the front-rear direction, and a tilt cylinder 10 that performs the front-back tilt is provided between the vehicle body 1 and the mast 6.
The mast 6 is composed of a pair of left and right outer masts 7 on the forklift side and a pair of left and right inner masts that are guided by the outer mast 7 and that can freely move up and down. A lift cylinder 18 is provided between the outer mast 7 and the inner mast. Is provided. The inner mast is provided with a lift bracket 9 that can be moved up and down on the rail. The position of the lift bracket 9 is controlled in the vertical direction via a chain wheel and a chain (not shown) by the power of a lift cylinder 18 that moves up and down along the inner mast.

The fork 4 is installed on the mast 6 via a lift bracket 9. The upper end of the fork 4 is pivotally attached to the upper part of the lift bracket 9. The fork 4 tilts with the pivoted portion 15 as a fulcrum.
Further, the lower rear portion of the fork 4 and the lift bracket 9 are connected by a hydraulic cylinder 14, and the rear surface of the fork 4 and the lift bracket 9 are configured to be in surface contact as shown in FIG.

  Here, the tilt device of the forklift according to the present embodiment will be described with reference to FIG. FIG. 2 schematically shows the tilt device of the forklift shown in FIG. 1, wherein 4 is a fork, 14 is a hydraulic cylinder, and 15 is a shaft attachment portion in which the upper end of the fork 4 is attached to a lift bracket 9. (Fulcrum). As shown in FIG. 2, by extending the hydraulic cylinder 14 connected to the lower back of the fork 4, the hydraulic cylinder 14 presses the fork 4, and the fork 4 is separated from the lift bracket and tilts upward. Note that the angle of tilting by the hydraulic cylinder 4 can be operated from the control unit, and can be maintained at that angle.

In the first embodiment, the fork 4 and the lift bracket 9 can be brought into surface contact, and only the fork 4 can be tilted without protruding the fulcrum.
Further, the fork 4 can be tilted separately from the tilting of the mast simply by providing the conventional forklift with a hydraulic cylinder. The number of hydraulic cylinders in this embodiment is one for each fork. The fork can be lifted forward (tilted backward) by providing only one hydraulic cylinder.

(Embodiment 2)
Next, the forklift tilt device according to the second embodiment will be described with reference to FIGS. 3 and 4.
As shown in FIGS. 3 and 4, the tilt device according to the second embodiment includes a fork 4, a lift bracket 9 that supports the fork 4, an arm 21 that connects the upper part of the lift bracket 9, and a lower part of the lift bracket 9. It is comprised with the hydraulic cylinder 22 which connects these. In addition, since the structure of the forklift other than that after the mast is the same as FIG. 1, the description is abbreviate | omitted.

  The lift bracket 9 is divided into a front bracket 9a and a rear bracket 9b, and is connected to the arm 21 and the hydraulic cylinder 22 as described above. Here, the arm 21 is described using a plate shape, but the shape is not limited as long as it connects the front bracket 9a and the rear bracket 9b. When no load is loaded on the fork 4, the hydraulic cylinder 22 is suspended by its own weight. Further, the front bracket 9a and the rear bracket 9b can be brought into surface contact with each other, and the front bracket 9a and the fork 4 are installed. The arm 21 is fixed and rotates along an arc.

  As shown in FIG. 4, when the fork 4 is tilted backward (upward), the hydraulic cylinder 22 is extended obliquely downward and the arm 21 is tilted as a fulcrum (A in FIG. 4). When the fork 4 is tilted forward (downwardly forward), the hydraulic cylinder 22 is contracted obliquely upward, and tilted with the lower end of the front bracket 9a as a fulcrum (B in FIG. 4).

Similarly to the first embodiment, when the hydraulic cylinder 22 has a malfunction in the hydraulic equipment, the fork 4 does not fall forward from the horizontal, so that the load can be prevented from dropping.
Further, in the second embodiment, the fork 4 can be tilted back and forth, and this also requires only one hydraulic cylinder.

(Embodiment 3)
Next, a tilt device for a forklift according to Embodiment 3 will be described with reference to FIG.
As shown in FIGS. 5A and 5B, the tilt device according to the third embodiment includes a fork 4, a lift bracket 9 that supports the fork 4, and a hydraulic cylinder 20. In addition, since the structure of the forklift other than that after the mast is the same as FIG. 1, the description is abbreviate | omitted.
The upper portion of the fork 4 is pivotally attached to the shaft 23. The fork 4 slides left and right on the shaft 23.
The hydraulic cylinder 20 is provided on the fork 4 via a slide plate 24. Therefore, even if the fork 4 slides left and right, the fork 4 can be lifted forward (tilted backward) by being pressed by the entire slide plate 24.

  FIG. 6 shows a usage example of the first to third embodiments described above. FIG. 6 shows an example of the cargo handling work of the forklift 100. The cargo handling work is performed in the state where the obstacle 25 exists in front of the forklift 100. In the first to third embodiments, since the mast 6 and the fork 4 are tilted separately, the cargo 26 can be handled only by the fork 4 as shown in FIG. Also, the cargo handling operation can be performed while the mast 6 is tilted forward, and the work radius can be increased only when the load of the load 26 is light.

When the working radius becomes large in this way, the risk of the vehicle body falling must be considered. Therefore, in the embodiment of the present invention, the interlock that detects the height of the mast, the inclination of the mast, and the load of the load mounted on the fork, and invalidates the command from the control unit provided in the vehicle body to regulate the cargo handling operation. Means. In relation thereto, a tilt device according to an embodiment of the present invention will be described with reference to a circuit diagram of the safety device of FIG.
A controller 36 configured as a computer including a CPU, a RAM, a ROM, and the like is mounted on the vehicle body. The controller 36 receives an operation signal operated by the tilt lever 16, executes a built-in program, and then outputs a control valve opening signal for controlling opening and closing of the control valve 35. The control valve 35 receives the signal and supplies hydraulic oil to the tilt cylinder 10. A predetermined hydraulic pressure acts on the tilt cylinder 10 to expand and contract, and the mast 6 connected to the tilt cylinder 10 tilts.

On the other hand, the control valve 35 also acts on the lift cylinder 34. Connected to the lift cylinder 34 is a cylinder pressure sensor 33 that detects the load of the load on the fork supported by a lift bracket that moves up and down along the mast 6.
Further, a mast height sensor 32 for detecting the height of the mast 6 and a mast inclination sensor 31 for detecting the inclination angle of the mast are connected to the mast 6. The cylinder pressure sensor 33, the mast height sensor 32, and the mast 6 are connected to the mast 6. The tilt sensor 31 sends an electrical signal to the controller 35.
As described above, if the height of the mast, the inclination of the mast, and the load of the load mounted on the fork are detected and an attempt is made to exceed the capacity of the forklift, the command from the tilt lever 16 is invalidated automatically. You can stop at. Thereby, it is possible to prevent the vehicle body from falling.

  According to the present invention, the tilt of the mast and the fork can be moved separately without structurally simple and without reducing the allowable load, and the cargo handling can be carried out without reducing the longitudinal displacement and reducing the stability of the vehicle body. Since the work can be performed, it can be widely applied from small to large forklifts, and can be suitably used particularly for large forklifts.

It is a side view of the forklift which concerns on Embodiment 1 of this invention. It is a side view which shows the tilting state of the forklift which concerns on Embodiment 1. FIG. 6 is a perspective view showing a forklift tilt device according to Embodiment 2. FIG. It is a side view which shows the tilting state of the forklift which concerns on Embodiment 2. FIG. (A) is a perspective view which shows the tilt apparatus of the forklift which concerns on Embodiment 3, (b) is a figure which shows a tilting state. It is a side view which shows the use condition which concerns on embodiment of this invention. It is a circuit diagram of a safety device concerning an embodiment of the present invention. It is a figure explaining the conventional forklift, (a) is a schematic side view of a forklift, (b) is a figure which shows a fork part. It is a schematic side view which shows the tilt structure of the conventional hinged fork.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body 2 Front wheel 3 Rear wheel 4 Fork 5 Operation part 6 Mast 9 Lift bracket 10 Tilt cylinder 14, 20, 22 Hydraulic cylinder 15 Axis attachment part (fulcrum)
21 Arm 24 Slide plate F Front overhang

Claims (6)

A mast standing in front of the vehicle body and tiltable in the front-rear direction; a lift bracket that moves up and down along the mast; a fork supported by the lift bracket; and a fluid pressure cylinder that tilts the fork; In the tilt device of the forklift that tilts the fork by extending and contracting the fluid pressure cylinder,
The lift bracket and the fork back surface are in surface contact with each other, and the fork upper end portion is pivotally attached to the lift bracket and includes a pivot attachment portion serving as a fulcrum for tilting the fork.
The fluid pressure cylinder provided on the back surface of the fork extends and presses the lower part of the back of the fork to be separated from the lift bracket, and the fork is tilted forwardly with the pivoting portion as a fulcrum. Forklift tilt device. A mast standing in front of the vehicle body and tiltable in the front-rear direction; a lift bracket that moves up and down along the mast; a fork supported by the lift bracket; and a fluid pressure cylinder that tilts the fork; In the tilt device of the forklift that tilts the fork by extending and contracting the fluid pressure cylinder,
The lift bracket is divided into a front bracket and a rear bracket, the front bracket and the rear bracket are in surface contact, and the front bracket and the fork are attached and provided,
The upper end of the front bracket is connected to the link arm, the lower end of the front bracket is connected to the rear bracket via the fluid pressure cylinder, and the fork is tilted back and forth by extending and contracting the fluid pressure cylinder. A forklift tilt device.   The fluid pressure cylinder is extended to tilt the fork forwardly with the link arm as a fulcrum, and the fluid pressure cylinder is contracted to tilt the fork to the front downward with the lower end of the front bracket as a fulcrum. The forklift tilt device according to claim 2.   The forklift tilt device according to any one of claims 1 to 3, wherein the fork is tilted separately from the mast.   A forklift comprising the forklift tilt device according to any one of claims 1 to 4.   Interlocking means for detecting the height of the mast, the inclination of the mast and the load of the load mounted on the fork and invalidating a command from the control unit provided in the vehicle body to regulate the cargo handling operation is provided. The forklift according to claim 5.

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