JP4222499B2 - forklift - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a forklift provided with a pallet locking device for locking a pallet lifted by a fork so as not to be accidentally displaced on the pallet during transportation.
[0002]
[Prior art]
FIG. 12 shows a side view of the order picking truck 1 that allows the cab to move up and down while the pallet is supported by a fork and performs a cargo handling operation such as picking a load at a high place. In the order picking truck 1, a cab 3 including a pair of forks 2 can be moved up and down integrally with the forks 2 along a mast device. With the fork 2 being inserted into the pallet 6, the pallet 6 is raised, and the operator moves onto the pallet 6 and performs a cargo handling operation with the shelf. Since this cargo handling work is often performed at a high place, if the pallet 6 swings on the fork 2, there is a risk that the operator may fall off. To prevent this, a pallet lock as shown in FIG. A bar 5 may be provided.
[0003]
That is, the bar 5 is provided so as to be able to turn up and down so as to be located inside the pedestal 4 at the bottom of the cab 3 and inside the fork 2. When the operator steps on the foot pedal 9 on the floor surface of the cab 3, the bar 5 is pivoted downward via a mechanical lock mechanism. As a result, the end of the bar 5 is pressed or pressed against the upper surface of the lower deck board of the pallet 6, and the pallet 6 is locked to prevent its swinging or sliding on the fork.
[0004]
[Problems to be solved by the invention]
However, in the lock operation of the pallet 6 by the operator's will, the lock operation may be forgotten when the pallet 6 is transported. In such a case, since the pallet 6 is not stable, the above-described fall accident is caused or cargo collapse occurs.
[0005]
The present invention has been provided in view of the above-described problems, and provides a forklift that can prevent the pallet from swinging or slipping, and can prevent forgetting to lock the pallet to improve the safety of cargo handling work. Is.
[0006]
[Means for Solving the Problems]
Therefore, as a first invention, in a forklift having a fork inserted into a pallet for placing a load and an elevating means for raising and lowering the fork, the pallet for locking the pallet inserted in the fork Locking means; pallet detection means for detecting that the pallet has been inserted into the fork; ascending operation detection means for detecting ascending movement of the fork; and after the pallet detection means detects insertion of the pallet, And a control means for driving the pallet locking means to lock the pallet when the raising operation detecting means detects an upward movement of the fork above a predetermined value , and the pallet locking means is provided by the control means. A driving device driven based on the signal, and the pallet is driven up and down by the driving device. To provide a forklift, characterized in that the and a lock bar lower deck board presses from above.
[0007]
According to the first aspect of the present invention, the pallet locking means is driven to lock the pallet when the ascending motion detecting means detects the ascending motion exceeding the predetermined value after the pallet detecting means detects the insertion of the pallet. Therefore, the pallet locking operation is automatically performed regardless of the will of the operator, and thus the above-described problem due to forgetting to lock the pallet does not occur. Further, since the pallet locking operation is performed after the pallet detection means detects the insertion of the pallet, the locking operation is not performed when the pallet is not inserted into the fork. Can be prevented. Further, since the pallet locking operation is performed when the fork raising operation exceeding a predetermined value is detected, the locking operation can be surely performed regardless of the placement height of the pallet to be transported. That is, in the first aspect of the present invention, the lock is not performed when the fork reaches a certain height from the ground, but the height of the fork at the time when the pallet detection means detects the insertion of the pallet exceeds a predetermined value. It is designed to lock when it is lifted by a distance of. Therefore, according to the first invention, for example, if the predetermined value is set to 20 cm, when a pallet at a height of 100 cm is lifted and conveyed from the ground, the height of the pallet is 120 cm from the ground by a fork. When it is raised to height, it is automatically locked. Of course, similarly, when a pallet at a height of 150 cm from the ground is transported, locking is performed when the height of the pallet is raised to a height of 170 cm from the ground. Therefore, even when a plurality of highly stacked pallets are lifted and conveyed, according to the first aspect, all the pallets can be reliably locked regardless of their heights.
[0008]
According to the first aspect of the invention, since the pallet locking operation is performed by pressing the lower deck board of the pallet from above with the lock bar, the pallet can be securely locked, and the pallet upper deck board can be locked. There is an advantage that a load can be placed on the front of the machine. Since the lock bar is driven up and down by the drive device, it can be automatically driven by the control device.
[0009]
As a second invention, the forklift according to the first invention, wherein the ascending motion detecting means detects an ascending motion of the fork above a predetermined value based on a driving time of the ascending / descending means. I will provide a.
[0010]
According to the second aspect of the invention, for example, when the lifting speed of the fork by the lifting / lowering means is a constant value, the product of the lifting speed and the driving time of the lifting / lowering means indicates that the fork has reached a height greater than a predetermined value. Since it can be detected, the first invention described above can be realized with a simple and inexpensive configuration. In addition, when the fork rising speed is not a constant value, a sensor for detecting the speed is added, and the fork has reached a height above a predetermined value by the product of the output of the sensor and the driving time of the lifting means. Can be detected. If the driving of the lifting / lowering means is determined by, for example, the operator's continued switch operation, the driving time described above is the time during which this switch is turned on, and therefore can be obtained very easily by known electrical means. .
[0011]
As a third invention, in the first invention, the elevating means has a motor as a drive source for elevating and driving the fork, and the ascending motion detecting means is based on the rotational speed of the motor. Provided is a forklift that detects an upward movement of the fork above a predetermined value.
[0012]
According to the third aspect of the invention, since the ascending distance of the fork is substantially proportional to the rotational speed of the motor, the rotational speed is detected by an encoder or the like and counted, and the Kunt value reaches a predetermined value. Since it can be determined that the fork has reached a height of a predetermined value or more, the first invention described above can be realized with a simple and inexpensive configuration.
[0013]
As a fourth invention, in the first invention, the control means releases the pallet lock by the pallet lock means based on an upward force that the lock bar receives from the lower deck board of the pallet. A forklift characterized by being provided.
[0014]
According to the fourth aspect of the invention, the lock of the pallet is automatically released when the pallet on the fork is wholesaled on the ground, which is very convenient for removing the pallet from the fork.
[0015]
As a fifth invention, in any one of the first to fourth inventions, the forklift is an order picking truck having a cab that moves up and down together with the fork, and the pallet locking means and the pallet detecting means are Provided is a forklift provided in the cab.
[0016]
According to the fifth aspect of the invention , since the pallet is prevented from swinging, the order picking truck that performs work at a high place can prevent the operator from falling off the pallet, and the effect is extremely great. Further, by providing the pallet lock means and the pallet detection means in the cab, the storage arrangement becomes easy.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, about the structure which has the same function as above-mentioned prior art, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 1 and FIG. 2 are perspective views of a forklift 1 called a so-called order picking truck in which an operator rides on a cab 3 or a pallet 6 and performs a cargo handling operation at a high place.
[0018]
A mast device 10 is provided at the center of the forklift 1, and along this mast device 10, a cab 3 for an operator to board is supported so as to be movable up and down. A pair of forks 2 is fixed to the rear side of the vehicle body of the cab 3 so as to protrude, and on the opposite side of the fork 2, that is, in front of the vehicle body, a motor for driving the vehicle body and a device for cargo handling are provided. A drive unit 11 including a hydraulic motor for driving the vehicle is disposed, and a fence-like head guard 12 is provided above the cab 3 for operator protection. A handle 13 is provided on the front left portion of the cab 3, and an operating device 18 including an accelerator for moving the vehicle body in the front-rear direction and a switch for raising and lowering the cab 3 and the fork 2 is provided on the right front portion. ing. Further, a substantially U-shaped safety bar 14 for protecting the operator is provided above the cab 3, and a brake pedal 16 is provided on the floor surface of the cab 3 (upper surface of the pedestal 4).
[0019]
Next, the configuration of the pallet locking device will be described with reference to FIGS. The pallet locking device 20 is housed and disposed in a flat pedestal 4 below the cab 3, and a lock bar 21 for locking the pallet is parallel to the fork 2 from the front plate 17 of the pedestal 4. Protruding. The lock bar 21 is formed in a substantially L shape facing each other in plan view, and a base portion is bolted to a plate-like bracket 23 so that the entire shape is formed in a substantially U shape by the two lock bars 21. It is in the state. In addition, an inclined portion 22 that is inclined downward toward the tip is formed at the top of the tip portion of both lock bars 21. The end of the bracket 23 is supported by a shaft 26 provided horizontally on the pedestal 4 so as to be pivotable up and down, so that the lock bar 21 can swing up and down around the shaft 26.
[0020]
A power cylinder 30 is disposed in the pedestal 4 in the longitudinal direction of the vehicle body. A rod 32 of the power cylinder 30 is illustrated by forward and reverse rotation of a motor 31 attached to the end of the power cylinder 30. It can be expanded and contracted through a gear that does not. In addition, on both sides of the power cylinder 30, an input detection sensor 28 that detects a state in which the rod 32 is housed and an output detection sensor 29 that detects a state in which the rod 32 is extended are provided. Note that the input detection sensor 28 and the output detection sensor 29 are constituted by magnetic sensors, for example.
[0021]
A link pair 34 is connected to the tip of the rod 32 via a shaft 36, and the lower end of the link pair 34 is rotatably connected to a shaft 35 supported by the pedestal 4. In addition, one end of a damper 40 is rotatably connected to the center of the link body 34 by a shaft 37, and the other end of the damper 40 is provided with a projecting portion 27 projecting from the upper surface of the bracket 23 and a shaft 41. It is connected via a pivot. The damper 40 absorbs a force applied to the lock bar 21 when the pallet 6 is locked as will be described later, and a coil spring is disposed inside.
[0022]
As shown in FIG. 4, in the state where the rod 32 of the power cylinder 30 is housed, the link body 34 is located on the left side of the drawing with the shaft 35 as the center, and is further connected to the link body 34. The damper 40 is urged to the left. As a result, the bracket 23 and the lock bar 21 swing counterclockwise about the shaft 26, and the lock bar 21 maintains a horizontal state in which the lock bar 21 is in the same vertical position as the fork 2 in a side view. In this state, when the power is applied to the motor 31 and the rod 32 of the power cylinder 30 is extended, the link body 34 is urged to the right in the drawing around the shaft 35 as shown in FIG. When the damper 40 is urged to the right, the bracket 23 swings clockwise about the shaft 26. That is, as indicated by the solid line, the lock bar 21 swings clockwise around the shaft 26 and presses or presses the upper surface of the lower deck board of the pallet 6 on the lower surface side of the tip of the lock bar 21. The pallet 6 is locked by the lock bar 21.
[0023]
Conversely, by reversing the direction of the voltage applied to the motor 31, the rod 32 of the power cylinder 30 is housed, the link body 34 rotates to the left about the shaft 35, and the damper 40 also moves to the left. By interlocking with each other, the bracket 23, that is, the lock bar 21, rotates counterclockwise around the shaft 26 and returns to the horizontal state.
[0024]
In addition, as shown in FIGS. 9 and 10, the pallet lock device 20 is provided with sensors for detecting the operation of each part. A magnet (a black member in the figure) 42 is provided on the back of the bracket 23 that fixes the lock bar 21. The magnet 42 is turned on (or turned off) to output a detection signal. A pallet detection sensor 43 including a magnetic sensor and a landing detection sensor 44 are provided. As shown in FIGS. 9A and 9B, a pallet detection sensor 43 that is turned on by the magnet 42 when the lock bar 21 is in a horizontal state is provided, and as shown in FIG. 9C. A landing detection sensor 44 that is turned on by the magnet 42 when the tip of the lock bar 21 turns downward by a predetermined angle is provided.
[0025]
FIG. 6 is a block diagram related to the control of the pallet locking device 20, and signals from the pallet detection sensor 43 and the landing detection sensor 44 are input to the control device 45 comprising the MPU, and the motor is operated by the control device 45 as described above. The pallet 6 is locked and released by the lock bar 21 by moving the rod 31 of the power cylinder 30 in the forward and reverse directions 31 and expanding and contracting. In the present invention, when the pallet 6 is locked by the lock bar 21, a signal from the landing detection sensor 44 and a signal which will be described later by operating the lift raising switch 51 are used. A hydraulic motor (see FIGS. 6 and 7) 52 as an elevating means for driving a cylinder (not shown) for elevating a cab 3 with an integrated fork 2 is composed of an encoder for detecting the rotational speed. A pulse counter 53 as an ascending operation detecting means is provided, and a signal from the pulse counter 53 is input to the control device 45. Further, when the pallet 6 is unlocked, an input detection sensor 28 that detects the position of the rod 32 of the power cylinder 30 and an output detection sensor 29 that detects the position of the rod 32 of the power cylinder 30 when the pallet 6 is locked. And a signal from a key switch 54 for turning on / off the power supply of the forklift 1 as a whole.
[0026]
Next, the operation of locking the pallet 6 by the pallet locking device 20 will be described with reference to FIGS. 8 and 9, and then the unlocking operation will be described. First, the operator turns on the key switch 54 as shown in step S1 of FIG. 8, and the fork 2 is inserted into the pallet 6 while the lock bar 21 remains horizontal as shown in FIG. 9A. Then, as shown in FIG. 9B, the tip of the lock bar 21 is inserted into the pallet 6 after the fork 2. When the fork 2 is further inserted, the upper surface of the inclined portion 22 of the lock bar 21 comes into contact with the end surface of the upper deck board 6a of the pallet 6, so that the lock bar 21 is inclined downward according to the inclination angle of the inclined portion 22. To go. 9C, the entire inclined portion 22 of the lock bar 21 enters the pallet 6, and the fork 2 completely enters the pallet 6, as shown in FIG. At the same time, the lock bar 21 rotates downward to move the position of the magnet 42 from the pallet detection sensor 43 to the position on the landing detection sensor 44 side.
[0027]
As a result, the pallet detection sensor 43 is turned off and the landing detection sensor 44 is turned on (see step S3 in FIG. 8), and the signals of these sensors 43 and 44 are taken into the control device 45. The control device 45 detects and determines that the pallet 6 has been inserted into the fork 2 when the pallet detection sensor 43 changes from on to off. After the pallet 6 is detected by the pallet detection sensor 43, as shown in step S4, when the operator turns on the lift raising switch 51, the hydraulic motor 52 for driving the fork 2 and the cab 3 up and down rotates. . The pulses generated by this rotation are counted by the pulse counter 53, and when the preset count number is reached, as shown in step S5, that is, the controller 45 indicates that the fork 2 has risen by a predetermined height or more. If detected, the process proceeds to step S6. In step S6, it is determined from the signals from the input detection sensor 28 and the output detection sensor 29 that the rod 32 of the power cylinder 30 has not come out. If the rod 32 has not come out (elongated), step S7 is executed. Move on.
[0028]
In step S7, the control device 45 causes the motor 31 to rotate forward, for example, to extend the rod 32 of the power cylinder 30 and further turn the lock bar 21 downward as described above. With the rod 32 of the power cylinder 30 extended, the tip of the lock bar 21 presses or presses the upper surface of the lower deck board 6b of the pallet 6 as shown in FIG. As a result, the pallet 6 is locked by the lock bar 21 (see step S7 in FIG. 8). If the key switch 54 is off in step S1 of FIG. 8, the process proceeds to step S2 to maintain the stopped state.
[0029]
Here, the ascending distance of the fork 2 until the fork 2 rises and the power cylinder 30 is driven is, for example, the height of the space inside the pallet 6 into which the fork 2 is inserted, or about half of that. . By setting the ascent distance of the fork 2 in this way, the pallet 6 can be locked immediately after being lifted by the fork 2. Of course, it is not limited to these, The rising distance can be set arbitrarily. The determination of the ascent distance is performed by presetting the number of rotation pulses of the hydraulic motor 52 corresponding to the ascent distance and counting the set number of pulses in step S5 of FIG.
[0030]
9D, since the magnet 42 is separated from the pallet detection sensor 43 and the landing detection sensor 44, the pallet detection sensor 43 and the landing detection sensor 44 are turned off. No. 45 controls the power cylinder 30 to maintain the lock of the pallet 6 by the lock bar 21 until a release signal described later is input.
[0031]
In this way, when the fork 2 is inserted into the pallet 6 and the pallet 6 is detected by the pallet detection sensor 43, and the operator further presses the lift raising switch 51 to raise the fork 2 above a certain level, the pallet locking device 20 Is driven, and the pallet 6 is automatically locked by the lock bar 21. For this reason, when an operator gets on the pallet 6 and performs a cargo handling operation, the pallet 6 is completely locked by the lock bar 21, so that the pallet 6 does not become unstable and can be safely operated. Can be done. Further, since the pallet 6 is automatically locked, the operator (operator) can forget to lock and can prevent an accident.
[0032]
Next, the unlocking operation of the pallet locking device 20 will be described. FIG. 10A shows a state in which the pallet 6 is locked by the lock bar 21 and the pallet 6 is lifted by the fork 2 to convey the load. In this state, the lock bar 21 is urged in the direction indicated by the arrow in the figure, and the magnet 42 is disengaged from the landing detection sensor 44. Therefore, both the landing detection sensor 44 and the pallet detection sensor 43 are in the off state. . Next, as shown in FIG. 10 (b), when the fork 2 is lowered and placed on the pallet 6 on the placing portion 47 such as a shelf or the ground (floor surface), the fork 2 is removed from the upper deck board 6 a of the pallet 6. Since it descends away, the position of the shaft 26 of the lock bar 21 also moves together. Therefore, the lock bar 21 rotates about the shaft 26 counterclockwise by an angle α1. The rotation of the lock bar 21 rotates the position of the magnet 42 to the position of the landing detection sensor 44, and the landing detection sensor 44 is turned on by the magnet 42.
[0033]
The on signal of the landing detection sensor 44 is input to the control device 45, and the control device 45 reverses the motor 31, for example, and stores the rod 32 of the power cylinder 30, and locks as shown in FIG. 10 (c). The bar 21 turns to a horizontal state, and the pallet 6 is unlocked. Note that the lock bar 21 is naturally in a horizontal state (unlocked state) in a state where the rod 32 of the power cylinder 30 is housed. Then, the magnet 42 corresponds to the position of the pallet detection sensor 43, the pallet detection sensor 43 is turned on, and the rod 32 of the power cylinder 30 is retracted, based on signals from the input detection sensor 28 and the output detection sensor 29. The control device 45 recognizes that the lock is released.
[0034]
Next, another embodiment of the present invention when the pallet 6 is locked will be described. Since the mechanical operation of the lock bar 21 is the same as that in FIG. 9, the control operation will be described with reference to the flowchart shown in FIG. In FIG. 11, the part different from the above-mentioned FIG. 8 is the part of step S15, and the other parts are the same as FIG. That is, the fork 2 is inserted into the pallet 6, the pallet 6 is detected by the landing detection sensor 44 (see step S13), and the operator pushes the push-button lift raising switch 51 (see step S14). Next, the process proceeds to step S15, and the time during which the lift raising switch 51 is pressed has reached a preset time, that is, the time required for the fork 2 to load the upper deck board 6a of the pallet 6. In this case, the control device 45 drives the power cylinder 30 via the motor 31. As a result, the lock bar 21 is pivoted downward to lock the pallet 6. That is, in this example, when the ascending speed of the fork 2 is a substantially constant value, the ascending height of the fork is obtained by the product of the ascending speed and the pressing operation time. If the lifting speed of the fork 2 is not constant, a sensor for detecting the speed is added, and the lifting height of the fork is obtained by the product of the output of the sensor and the pressing operation time. A comparison determination may be made.
[0035]
【The invention's effect】
As described above, according to the present invention, the pallet locking operation is automatically performed regardless of the will of the operator, and thus the above-described problem due to forgetting to lock the pallet does not occur. Further, according to the present invention, the pallet locking operation is performed when a fork raising operation exceeding a predetermined value is detected, so that the pallet locking operation can be reliably performed regardless of the placement height of the pallet to be transported. it can.
[Brief description of the drawings]
FIG. 1 is a perspective view seen from the rear of a forklift according to an embodiment of the present invention.
FIG. 2 is a perspective view seen from the front of the forklift according to the embodiment of the present invention.
FIG. 3 is a plan view of a cab showing the configuration of the pallet locking device according to the embodiment of the present invention.
FIG. 4 is a side view of the cab showing the configuration of the pallet locking device according to the embodiment of the present invention.
FIG. 5 is a main part configuration diagram of the pallet locking device according to the embodiment of the present invention.
FIG. 6 is a block diagram related to the pallet locking device according to the embodiment of the present invention.
FIG. 7 is a schematic side view of a forklift according to an embodiment of the present invention.
FIG. 8 is a flowchart showing a control operation when locking is performed in the embodiment of the present invention.
FIGS. 9A to 9D are operation explanatory views when the pallet is locked by the lock bar in the embodiment of the present invention.
FIGS. 10A to 10C are operation explanatory views when unlocking a pallet according to the embodiment of the present invention.
FIG. 11 is a flowchart showing another control operation when the pallet is locked in the embodiment of the present invention.
FIG. 12 is a side view of a forklift when a problem of a conventional example is described.
FIG. 13 is an explanatory diagram when locking is performed according to a conventional example.
[Explanation of symbols]
1 Forklift (order picking truck)
2 Fork 3 Driver's cab 6 Pallet 20 Pallet lock device (pallet lock means)
21 Lock bar 30 Power cylinder (drive device for pallet locking means)
42 Magnet 44 Pallet detection sensor (pallet detection means)
45 Control device (control means)
51 Lift raising switch 52 Hydraulic motor (lifting means)
53 Pulse counter (rising motion detection means)

Claims (5)

In a forklift having a fork inserted into a pallet for placing a load and an elevating means for raising and lowering the fork, pallet locking means for locking the pallet inserted in the fork, and the fork Pallet detection means for detecting that a pallet has been inserted, ascent action detecting means for detecting ascent action of the fork, and after the pallet detection means detects insertion of the pallet, the ascent action detection means Control means for driving the pallet locking means to lock the pallet when detecting an upward movement exceeding a predetermined value , and the pallet locking means is driven based on a signal from the control means And the lower deck board of the pallet moved up and down by the drive device Forklift, characterized in that a lock bar for pressing Ri.   2. The forklift according to claim 1, wherein the ascending motion detecting means detects an ascending motion of the fork exceeding a predetermined value based on a driving time of the lifting means.   The elevating means has a motor as a drive source for raising and lowering the fork, and the elevating operation detecting means detects an elevating operation of the fork above a predetermined value based on the number of rotations of the motor. The forklift according to claim 1, wherein the forklift is provided. 2. The forklift according to claim 1 , wherein the control unit is configured to release the lock of the pallet by the pallet lock unit based on an upward force that the lock bar receives from the lower deck board of the pallet. The forklift of the order picking truck having a cab which integrally lift together with the fork, the pallet locking means and the pallet detection means of claims 1 to 4, characterized in that provided in the cab A forklift according to any one of the above.

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