JP2004196445A - Forklift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forklift that automatically locks a pallet inserted to a fork to absolutely prevent oscillation of the pallet. <P>SOLUTION: Even when a landing detection sensor 46 for detecting the pallet to land on a floor, rack, and so on outputs a detection signal, the forklift does not always transmit the detection signal to a lock mechanism control means 23. The forklift has a gate unit 50 placed between the landing detection sensor 46 and the lock mechanism control means 23. The forklift allows, with the gate unit 50, the detection signal outputted from the landing detection sensor 46 to pass the gate to reach the lock mechanism control means 23 only when a lift control means 10 outputs a command signal for lowering the fork. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a forklift, and more particularly, to a forklift provided with a pallet lock device for locking a pallet.
[0002]
[Prior art]
In an order picking type forklift, which is a type of forklift, a fork and a cab are integrally moved up and down along a mast. In such an order picking type forklift, a fork is transported to a predetermined place while inserted into the pallet, and after the pallet is lifted, an operator moves on the pallet and loads and unloads goods to and from the shelf. Do the work.
[0003]
In this way, in cargo handling work using an order picking type forklift, work is often performed at high places with the cab raised, so simply supporting the pallet with a fork makes the pallet unstable, and If it swings, stable cargo handling cannot be performed, and in the worst case, there is a possibility that the worker may fall. Therefore, by providing a lock member in parallel with the fork and manually pulling a lever provided on the cab, or by stepping on a foot pedal provided on the floor surface of the cab, the lock member is interlocked therewith. Is pivoted downward away from the fork, whereby the lower surface of the upper plate of the pallet is pressed by the fork, and the upper surface of the lower plate is pressed by the lock member. The following configuration is proposed in the following patent document.
[0004]
[Patent Document 1]
JP-A-11-228085 [Patent Document 2]
JP 2001-316095 A [Patent Document 3]
JP 2002-12397 A [Patent Document 4]
JP 10-291790 A
[Problems to be solved by the invention]
However, a configuration in which the operator locks the pallet by operating a manual lever or a foot pedal each time is not sufficient to ensure safety, because the locking operation may be forgotten.
[0006]
For this reason, the inventor of the present application automatically locks the pallet performed by the operator by detecting that the pallet has been inserted into the fork with a sensor and rotating the lock lever up and down based on the detection output. Tried to lock it. However, when the vehicle travels on a rough road surface, the pallet inserted into the fork vibrates up and down, and the sensor reacts to cause a malfunction of the lock lever.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a forklift capable of automatically locking a pallet inserted into a fork and reliably preventing the pallet from swinging.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present invention is configured as follows.
[0009]
The invention according to claim 1 is a forklift provided with a lock mechanism for locking a pallet inserted into a fork, a pallet detection sensor for detecting that the fork is inserted into the pallet, and a pallet for unloading the pallet. A landing detection sensor for detecting that the fork has landed at a predetermined position, lifting / lowering operation means for outputting a command signal for raising / lowering the fork, a fork lowering command signal of the lifting / lowering operation means, and the landing detection sensor Gate means for outputting an unlock signal when both of the detection signals are output, and the pallet is locked based on a detection signal of the pallet detection sensor, and the gate is locked based on an unlock signal of the gate means. Lock mechanism control means for controlling the lock mechanism so as to unlock the pallet. It is characterized in.
[0010]
According to the invention, the pallet is automatically locked, so that the lock operation is not forgotten as in the related art, and the pallet can be securely locked. In addition, the lock is released when both the instruction of lowering the fork by the operator and the landing of the pallet are performed. Therefore, the lock is not released by the swing of the pallet accompanying the vehicle running.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the signal extending means for extending the fork lowering command signal for a predetermined period from the time when the operation for lowering the fork by the raising / lowering operating means is stopped is provided. It is characterized by having.
[0012]
According to the present invention, since the extension means for extending the signal of the descending instruction for a predetermined period from the time when the fork descending instruction operation by the operator is stopped is provided, the coasting is performed after releasing the fork descending switch. Even when the pallet lands, the lock on the pallet can be released without fail.Therefore, it is not necessary to keep pressing the down switch for a long time or to press the switch many times, thereby reducing the burden on the operator. it can.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0014]
The order picking type forklift 1 shown in FIGS. 4 to 7 is provided with a cab 3 having a pair of forks 2 so as to be able to move up and down integrally with the forks 2 along a mast 4. Above the cab 3, a safety bar 5 and a head guard 6 for protecting workers are provided.
[0015]
On the other hand, an operation panel 9 is provided on the front side of the cab 3 on the vehicle body. The operation panel 9 includes a lifting operation means 10 for raising and lowering the fork 2 and the cab 3, an accelerator lever 11 for speed adjustment, Various instruments such as a battery capacity meter which is not used, and a steering handle 12 and the like are arranged. A pedestal 13 of the cab 3 is provided with a brake petal 14.
[0016]
Further, as shown in FIG. 5, a traveling mechanism 17 having a traveling motor and the like driven in accordance with the operation of the accelerator lever 11 and an up switch 10a and a down switch 10b constituting the up / down operation means 10 are provided inside the vehicle body. An elevating mechanism 18 provided with an elevating motor and the like driven in accordance with an operation, and an operation control means 19 for controlling these mechanisms 17 and 18 are provided, and a battery (not shown) serving as a driving source for these parts is provided. ) Is installed.
[0017]
Further, the forklift 1 is provided with a pallet lock device for automatically locking the pallet. As shown in FIG. 7, the pallet lock device includes a lock mechanism 22 for mechanically locking the pallet 24 in cooperation with the fork 2 and a lock mechanism control means including a microcomputer for controlling the operation of the lock mechanism 22. 23.
[0018]
As shown in FIG. 6, the lock mechanism 22 has a pair of left and right lock bars 25 that contact the pallet 24 and protrude from the end of the pedestal 13 of the cab 3 along the fork 2. The tips of the lock bars 25 are formed in a wedge shape, and project slightly above the upper surface of the fork 2 when the lock bar 25 is in a horizontal state. A base end of the lock bar 25 is fixed to a bracket 26 by bolts or the like, and a distal end of the bracket 26 is vertically pivotally mounted by a shaft 27 supported by the pedestal 13.
[0019]
On the other hand, a power cylinder 30 for driving the lock bar 25 is disposed in the pedestal 13 of the cab 3 along the vehicle longitudinal direction, and a motor 31 is connected to a rod of the power cylinder 30 via a gear (not shown). The power cylinder 30 is expanded and contracted by the forward and reverse rotation of the motor 31. At both ends of the power cylinder 30, an input detection sensor 32 for detecting the retracted state and an output detection sensor 33 for detecting the extended state are provided, respectively.
[0020]
One end of a link member 35 is connected to a distal end of the power cylinder 30 via a shaft 34, and the other end of the link member 35 is rotatably connected to a shaft 37 supported by the pedestal 13. One end of a damper 38 is rotatably connected to a substantially central position of the link member 35 by a shaft 39, and the other end of the damper 38 is connected to a connecting plate 40 protruding from the upper surface of the bracket 26 by a shaft 41. It is rotatably connected via a. A coil spring is built in the damper 38, and absorbs a force so that an excessive force is not applied to the lock bar 25 and the power cylinder 30 when the pallet 24 is locked.
[0021]
Further, as shown in FIGS. 7 and 8, the pallet lock device 21 uses a magnet 44 attached to the back of the bracket 26 fixing the lock bar 25 and a magnet 44 attached to the pedestal 13 side. A pallet detection sensor 45 and a landing detection sensor 46 that are turned on / off are provided. The outputs of the detection sensors 45 and 46 are input to the lock mechanism control means 23.
[0022]
The pallet detection sensor 45 detects that the fork 2 is inserted into the pallet 24. The pallet detection sensor 45 is on when the lock bar 25 is in the horizontal state, and the fork 2 is fully inserted into the pallet 24. The lock bar 25 is turned off when the lock bar 25 is tilted. The landing detection sensor 46 detects that the pallet 24 has landed on a shelf, the ground, or the like. The pallet 24 is off when the pallet 24 is transported, and the pallet 24 lands on the shelf or the like, and the fork 2 is lowered. The lock bar 25 is turned on when the lock bar 25 is turned toward the original horizontal position.
[0023]
FIG. 8 is a flowchart showing a procedure for locking and unlocking the pallet 24 by the pallet lock device 21 having the above configuration.
[0024]
When the power cylinder 30 is in the retracted state, the damper 38 is drawn toward the link member 35, so that the lock bar 25 is in a horizontal state as shown in FIG. 8A. At this time, the magnet 44 faces the pallet detection sensor 45, and therefore, the pallet detection sensor 45 is on.
[0025]
In this state, as shown in FIG. 8B, when the fork 2 is inserted into the pallet 24, the upper surface of the tip of the lock bar 25 contacts the upper inner surface 24a of the pallet 24, and the insertion amount of the fork 2 becomes large. As it becomes, the lock bar 25 gradually inclines downward. When the magnet 44 moves away from the position facing the pallet detection sensor 45 by the rotation of the lock bar 25, the detection output of the pallet detection sensor 45 is turned off. Accordingly, the lock mechanism control unit 23 rotates the motor 31 in the normal direction. Then, the rod of the power cylinder 30 is extended.
[0026]
As the rod of the power cylinder 30 is extended, the damper 38 is pushed by the link member 35, whereby the bracket 26 and the lock bar 25 are pivoted downward about the shaft 27, and the space between the bracket 26 and the lock bar 25 is expanded. . Then, as shown in FIG. 8C, after the lower end of the lock bar 25 comes into contact with the lower inner surface 24b of the pallet 24, the power cylinder 30 is further extended to a certain extent. Is detected by the detection sensor 33, the lock mechanism control means 23 stops the motor 31 in response to this. Thus, the upper and lower inner surfaces 24a and 24b of the pallet 24 are locked by the fork 2 and the lock bar 25. At this time, since the magnet 44 is away from the position facing the landing detection sensor 46, the detection output of the landing detection sensor 46 is off.
[0027]
On the other hand, after carrying out cargo handling work such as transportation and loading / unloading of the load while the pallet 24 is locked in this manner, as shown in FIG. When the pallet 24 lands at a predetermined position 47, the fork 2 descends away from the upper inner surface 24a of the pallet 24, and the position of the shaft 27 of the lock bar 25 also descends. Then, since the damper 38 contracts, the lock bar 25 pivots upward about the shaft 27.
[0028]
When the magnet 44 comes to a position facing the landing detection sensor 46 by the rotation of the lock bar 25, the detection output of the landing detection sensor 46 is turned on. Accordingly, the lock mechanism control means 23 rotates the motor 31 in the reverse direction. Then, the rod of the power cylinder 30 is retracted.
[0029]
As shown in FIG. 8 (e), as the power cylinder 30 is retracted, the damper 38 is pulled toward the link member 35, so that the bracket 26 and the lock bar 25 pivot upward about the shaft 27. Then, the lock bar 25 returns to the horizontal state. In this state, since the input detection sensor 32 detects that the power cylinder 30 has retracted to the original position, the lock mechanism control means 23 stops the motor 31 in response to this.
[0030]
FIG. 1 is a block diagram showing a main configuration of an operation control system of a forklift and a control system of a pallet lock device according to a first embodiment of the present invention. The components corresponding to those shown in FIGS. Have the same reference numerals.
[0031]
Note that the entire configuration of the forklift and the basic parts of the lock mechanism constituting the pallet lock device are the same as those described with reference to FIGS. The forklift according to the first embodiment includes a lifting operation unit 10 for lifting and lowering the fork 2 and the cab 3 and an accelerator lever 11 for speed adjustment, as described with reference to FIG. Mechanism 17 provided with a traveling motor and the like driven by moving, a lifting mechanism 18 provided with a lifting motor and the like driven in response to the operation of a lifting switch 10a and a lowering switch 10b constituting the lifting operation unit 10, An operation control unit 19 that controls each of the mechanisms 17 and 18 is provided.
[0032]
Further, the forklift of the first embodiment is provided with a pallet lock device 21 for automatically locking the pallets as shown in FIG. The pallet lock device 21 includes a lock mechanism 22 for mechanically locking the pallet 24 in cooperation with the fork 2, a pallet detection sensor 45 for detecting that the fork 2 has been inserted into the pallet 24, The pallet 24 is locked on the basis of the detection output of the landing detection sensor 46 and the detection output of the pallet detection sensor 45, and the pallet 24 is locked on the basis of the detection output of the landing detection sensor 46. And a lock mechanism control means 23 for controlling the lock mechanism 22 so as to release the lock.
[0033]
Further, the pallet lock device 21 allows the passage of the detection signal output from the landing detection sensor 46 when the fork lowering command signal is output from the lowering switch 10b of the raising and lowering operation means 10 to allow the lock mechanism control means An AND gate 50 is provided as a gate means for giving to the gate 23.
[0034]
Other configurations are the same as those shown in FIGS. 4 to 8, and a detailed description thereof will be omitted.
[0035]
In this configuration, the lock operation and the unlock operation of the pallet 24 by the pallet lock device 21 are basically the same as those of the related art. In particular, when the fork 2 is lowered by operating the lowering switch 10b of the raising and lowering operation means 10 to drive the raising and lowering mechanism 18, the pallet 24 is not moved until the pallet 24 lands on a predetermined position such as a floor or a shelf. Since the fork lowering command signal from the lowering switch 10b is applied to the AND gate 50, a lock release signal is output from the AND gate 50. Therefore, in this state, when the lock bar 25 turns and the detection output of the landing detection sensor 46 is turned on, the lock mechanism control means 23 rotates the motor 31 in reverse to retract the power cylinder 30 accordingly. The pallet 24 is unlocked.
[0036]
Further, when carrying a load while the pallet 24 is locked by the pallet lock device 21, the fork lowering command signal is not output from the lowering switch 10b, and the AND gate 50 is closed. . Therefore, even if the detection output of the landing detection sensor 46 is turned on and a detection signal is output, the detection signal is blocked by the AND gate 50 even if the pallet 24 vibrates greatly depending on the condition of the road surface or the like. It is not input to the lock mechanism control means 23. Therefore, the locked state of the pallet 24 is prevented from being unexpectedly released during the transportation.
[0037]
(Embodiment 2)
FIG. 2 is a block diagram showing a main configuration of an operation control system of a forklift and a control system of a pallet lock device according to a second embodiment of the present invention. The components corresponding to those shown in FIGS. Have the same reference numerals.
[0038]
The feature of the second embodiment is that, in addition to the AND gate 50 as the gate means provided in the first embodiment, the output period of the fork lowering command signal by the lowering switch 10b of the raising / lowering operating means 10 and the output period of this command. Signal extending means 51 for extending the fork lowering command signal for a further predetermined period from the time when the operation for stopping is stopped. Although not shown, the signal extending means 51 includes, for example, a one-shot circuit triggered in response to a fall of a fork lowering command signal, an output of the lowering switch 10b of the lifting / lowering operating means 10, and an output of the one-shot circuit. Are combined with an OR gate that outputs both.
[0039]
By the way, when the fork 2 is lowered to land the pallet 24 at a predetermined position on the floor or the like in a normal cargo handling operation, the lowering switch 10b is turned off before the pallet 24 is completely landed on the floor or the like. The pallet 24 may be turned off to stop the command signal for lowering the fork, and thereafter, the operation of landing the pallet 24 by the inertia of the lowering of the fork 2 may be performed.
[0040]
In this case, according to the configuration of the first embodiment, when the detection signal is output from the landing detection sensor 46, the output of the fork lowering command signal is already stopped. The detection signal is not applied to the lock mechanism control means 23. Therefore, the lock of the pallet 24 is not released. To release the lock, it is necessary to operate the lowering switch 10b again to output a fork lowering command signal so that the detection output of the landing detection sensor 46 passes through the AND gate 50. Operation becomes troublesome twice.
[0041]
On the other hand, in the second embodiment, as shown in the timing chart of FIG. 3, in order to land the pallet 24 by the descent inertia of the fork 2, the fork descent outputted from the descent switch 10b of the elevating operation means 10 is performed. Is stopped (time tb), the signal extending means 51 continuously outputs a gate signal for opening the gate to the AND gate 50 for a predetermined period T0 from that time.
[0042]
Therefore, even if a detection signal is output from the landing detection sensor 46 in a state where the command signal for fork lowering is not already output in order to lower the fork 2 by inertia, the AND gate 50 is open. The detection signal from the detection sensor 46 passes through the AND gate 50 and is applied to the lock mechanism control means 23. Therefore, when the pallet 24 lands on a predetermined position such as a floor surface, the locked state of the pallet 24 is released. Thereby, the trouble of operating the down switch 10b twice can be saved, and the burden on the operator can be reduced.
[0043]
【The invention's effect】
According to the first invention, the pallet is automatically locked, so that the lock operation is not forgotten as in the related art, and the pallet can be securely locked. In addition, the lock is released when both the instruction of lowering the fork by the operator and the landing of the pallet are performed. Therefore, the lock is not released by the swing of the pallet accompanying the vehicle body traveling.
[0044]
In the second invention, since the extension means for extending the signal of the descending instruction for a predetermined period from the time when the operation of instructing the descending of the fork by the operator is stopped is provided, the coasting is performed after releasing the descending switch of the fork. Even when the pallet lands, the lock on the pallet can now be released without fail, so there is no need to keep pressing the down switch for a long time or repeatedly, reducing the burden on the operator. it can.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of an operation control system of a forklift and a control system of a pallet lock device according to Embodiment 1 of the present invention.
FIG. 2 is a block diagram showing a main configuration of an operation control system of a forklift and a control system of a pallet lock device according to Embodiment 2 of the present invention.
FIG. 3 is a timing chart for explaining an operation according to the second embodiment of the present invention;
FIG. 4 is a perspective view showing an overall configuration of an order picking type forklift according to Embodiment 1 or 2 of the present invention.
FIG. 5 is a block diagram showing a configuration of a forklift operation control system according to Embodiment 1 of the present invention.
FIG. 6 is a side view of a lock mechanism of the pallet lock device according to the first embodiment of the present invention.
FIG. 7 is a block diagram illustrating a configuration of a pallet lock control system of the pallet lock device according to the first embodiment of the present invention.
FIG. 8 is an explanatory diagram of an operation of locking and unlocking the pallet by the pallet lock device according to the first embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Forklift 2 Fork 10 Elevating operation means 21 Pallet lock device 22 Lock mechanism 23 Lock mechanism control means 24 Pallet 45 Pallet detection sensor 46 Landing detection sensor 50 AND gate (gate means)
51 Signal extension means

Claims (2)

In a forklift equipped with a lock mechanism for locking a pallet inserted into a fork,
A pallet detection sensor that detects that the fork has been inserted into the pallet;
A landing detection sensor that detects that the pallet has landed at a predetermined position for unloading,
Lifting operation means for outputting a command signal for raising or lowering the fork;
Gate means for outputting a lock release signal when a fork lowering command signal of the lifting operation means and a detection signal of the landing detection sensor are both output,
Lock mechanism control means for locking the pallet based on a detection signal of the pallet detection sensor, and controlling the lock mechanism to unlock the pallet based on an unlock signal of the gate means;
A forklift comprising: 2. The forklift according to claim 1, further comprising signal extension means for extending a fork lowering command signal for a predetermined period from a point in time when the operation for commanding the fork lowering by the lifting / lowering operating means is stopped.

Images