JP4767510B2 - forklift - Google Patents

Description

  The present invention relates to a forklift that inserts a fork into a pallet for placing a load and lifts the fork to convey the load.

  The forklift may be provided with means called a pallet lock device in order to prevent the pallet inserted into the fork from swinging or sliding unexpectedly. There are two types of paretrok devices: a manual type that is operated by an operator with a hand or a foot, and an automatic type that is automatically operated in accordance with a cargo handling operation of a forklift. In recent years, the automatic type is becoming mainstream. According to this automatic pallet locking device, the pallet is automatically locked when necessary, that is, fixed to the fork, and unlocking is also automatically performed.

  Examples of such an automatic pallet locking device are described in, for example, the following patent documents. The invention described in Patent Document 1 detects the position of the fork with respect to the pallet, and locks the pallet when the fork comes close to the upper deck board of the pallet. The invention described in Patent Document 2 detects the insertion of a pallet into the fork and locks the pallet when the pallet is inserted into the fork. The pallet locking device includes a lock bar that presses the lower deck board from above on the pallet, locks the pallet by pressing the lock bar, and releases the lock by retracting the lock bar upward.

The inventions of these patent documents are provided mainly with the timing when the pallet is locked, and the operation of releasing the lock by the pallet lock device is based on the force that the lock bar receives from below when the pallet is grounded. Done. The invention for releasing the lock based on the force received by such a lock bar is described in detail in Patent Document 3.
JP 2003-252598 A JP 2003-252596 A JP 2003-238088 A

  However, since the force received by the lock bar changes due to vehicle body vibration when the forklift travels, there is a possibility that malfunction occurs when the vehicle body undergoes large vibrations. In order to prevent malfunctions, it is possible to set the lock bar so that it will not be unlocked unless it receives a relatively large force. There is also a problem that the reliable operation of the pallet locking device is not guaranteed. Conventional pallet locking devices have been developed with an emphasis on the locking operation, and it cannot be said that sufficient consideration has been given to the unlocking operation.

  This invention pays attention to such a problem, and was provided for the purpose of ensuring that the unlocking operation of the pallet in the forklift can be performed reliably.

  The present invention does not focus on the fact that when the pallet inserted into the fork is placed on the floor surface or the top surface of the rack for unloading, the lock bar or pallet receives an upward force due to grounding. The focus is on the fork moving away from the upper deck board of the pallet. In other words, this is achieved by detecting whether or not the pallet is grounded as a change appearing on the non-grounded side, that is, the upper deck board, instead of detecting it as a change appearing on the pallet grounding side, that is, the lower deck board. .

In order to achieve the above object, the present invention provides a forklift having a fork inserted into a pallet for placing a load, and an elevating means for elevating the fork. A lock bar that presses the upper surface; and a drive device that drives the lock bar. The lock bar presses the lower deck board of the pallet to lock the pallet, and the pressed lock bar is Pallet locking means for releasing the lock of the pallet by moving away from the side deck board, and is supported so as to be pivotable up and down. Usually, the horizontal state is maintained by the force of the spring, and the predetermined state is higher than the upper surface of the fork in the horizontal state. A detection bar formed with a protrusion protruding upward by a dimension, and disposed below the base end of the detection bar; The first sensor for detecting the detection bar in the horizontal state and the upper end of the base end of the detection bar, and the protrusion of the detection bar is pressed against the lower surface of the upper deck board of the pallet and moves downward. A pallet detection device comprising: a second sensor for detecting the detection bar turned by the rotation; and a pallet lock means for receiving the detection signal of the detection bar by the second sensor and locking the pallet with the lock bar. A control device that drives the drive device or drives the drive device of the pallet locking means to receive the detection signal of the detection bar by the first sensor and release the lock of the pallet by the lock bar; When the fork inserted into the pallet is raised, the upper surface of the fork contacts the lower surface of the upper deck board of the pallet, At this time, the detection bar swung by the protrusion of the detection bar being pressed against the lower surface of the upper deck board of the pallet and moving downward is detected by the second sensor, so that the detection from the second sensor is performed. Upon receiving the signal, the control device drives the drive device to lock the pallet, lowers the fork inserted into the pallet, and lowers the fork even when the pallet is placed on the floor. When the fork is separated from the lower surface of the upper deck board of the pallet, and the detection bar returned to the horizontal state by the force of the spring is detected by the first sensor, the detection signal from the first sensor The forklift is characterized in that the control device that has received the drive drives the drive device to unlock the pallet. .

According to the invention, the detecting means for detecting contact / separation between the upper surface of the fork and the upper deck board of the pallet is provided, and the upper surface of the fork and the upper deck board of the pallet are mutually connected by the output of the detecting means. When it is detected that the pallet is separated, the pallet is unlocked, so that the malfunction of the pallet lock device is not caused by vibration of the vehicle body, and the reliable unlocking operation of the pallet lock device can be ensured.

  As described above, according to the present invention, it is possible to ensure a reliable unlocking operation of the pallet locking device without causing malfunction due to vibration of the vehicle body, etc., so that the reliability of the automatic pallet locking device can be improved. There is an effect.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an order picking truck as an example of a forklift according to the present invention.

  A mast 2 is erected in the center of the vehicle body 1, and a driver's cab 3 on which an operator is boarded moves up and down along with the mast 2 together with a pair of forks 4 fixed to the driver's cab 3. On the front side of the vehicle body, that is, on the side opposite to the fork 4, a storage unit 5 that houses a motor for driving the vehicle body 1 and a hydraulic motor for driving the cab 3 and the fork 4 up and down is arranged. Has been. The hydraulic motor, the mast 2 and the like correspond to the lifting means in the present invention. In addition, a head guard 6 is provided above the cab 3, and a driving operation device 7 including an accelerator device is provided in the front center portion of the cab 3, and a substantially U-shaped safety for operator protection is provided. A bar 8 is arranged so as to be pivotable up and down. The operator rides on the floor 9 of the cab 3 and stands in the safety bar 8 to operate the driving operation device 7 with the back facing the fork 4 to drive the vehicle body 1 and drive The stand 3 and the fork 4 can be raised and lowered integrally. Reference numerals 10 and 11 denote parts of a pallet lock device and a pallet detection device which will be described later.

  Next, the configuration of the pallet lock device 10 and the pallet detection device 11 will be described with reference to FIGS. 2 is a view of the floor 9 of the cab 3 as viewed from below, FIG. 3 is a longitudinal side view of the floor 9 showing the configuration of the pallet locking device 10, and FIG. 4 shows the configuration of the pallet detection device 11. FIG. 5 is a vertical sectional side view of the floor 9 shown, and FIG.

  As shown in FIG. 3, the pallet lock device 10 mainly includes a lock bar 20 for pressing the pallet P and a lock drive device 21 for driving the lock bar 20 to turn. As shown in FIG. 2, the lock bar 20 has a substantially L shape in plan view or bottom view, and is arranged in parallel close to each inner side of the pair of left and right forks 4. When inserted into the insertion hole P3, the fork 4 is inserted into the insertion hole P3. The lock driving device 21 includes a cylinder device 22 that extends and contracts, and a transmission device 23 that transmits the expansion and contraction operation of the cylinder device 22 to the lock bar 20, and is disposed inside the floor 9.

  The cylinder device 22 is electrically operated or utilizes fluid pressure, and performs an operation of extending or contracting the cylinder rod 24 in the left-right direction in FIG. The transmission device 23 includes a first plate 26 connected to the cylinder rod 24 and the first shaft 25, and a second plate 28 fixed to the base end portion of the lock bar 20 and connected to the second shaft 27. The connecting rod 29 is connected to the central portion of the first plate 26 and the upper end portion of the second plate 28, respectively. The first shaft 25 and the second shaft 27 are supported on the floor 9. When the cylinder rod 24 of the cylinder device 22 extends rightward in FIG. 3, the first plate 26 pivots rightward about the first shaft 25, whereby the connecting rod 29 moves rightward to move the second plate. 28 turns to the right about the second shaft 27. Then, the lock bar 20 fixed to the second plate 28 pivots downward by a predetermined angle around the second shaft 27, that is, in the clockwise direction in FIG.

  When the cylinder rod 24 of the cylinder device 22 is contracted, the lock bar 20 pivots around the second shaft 27 upward, that is, counterclockwise in FIG. Return to the state. In this return state, the lock bar 20 is positioned and stopped by a stopper (not shown) so that the upper end edge 20a of the lock bar 20 and the upper surface 4a of the fork 4 have a horizontal posture of the same height. The connecting rod 29 is provided with a spring 30 for allowing the rod 29 to expand and contract so that a slight elastic force can be applied to the pressing operation of the lock bar 20 against the pallet P, as will be described later. It has become.

  As shown in FIG. 4, the pallet detection device 11 includes a pair of detection bars 32 supported by a shaft 31 provided on the floor 9 so as to be able to turn up and down, and a first and a second detecting bar 32. It mainly comprises second proximity sensors 33 and 34. As shown in FIG. 2, the detection bar 32 is disposed between each fork 4 and each lock bar 20, so that the fork 4 and the lock bar 20 are inserted into the insertion hole P3 of the pallet P. Together with these, it is inserted into the insertion hole P3.

  A spring 35 extending between the floor 9 and the base end 32b of the detection bar 32, that is, the side opposite to the pallet P inserted into the fork 4 is engaged. The detection bar 32 normally maintains the horizontal state shown in FIG. A protrusion 32a is formed on the upper portion of the detection bar 32. In the horizontal state, the protrusion 32a protrudes above the upper surface 4a of the fork 4 by a predetermined dimension.

  The first sensor 33 is disposed below the base end portion 32b of the detection bar 32, and the second sensor 34 is disposed above the base end portion 32b. When the detection bar 32 is in the horizontal state, the first sensor 33 detects the bar 32 and outputs an ON signal, and the second sensor 34 outputs an OFF signal so as not to detect the bar 32. Further, when the bar 32 is turned clockwise by a predetermined angle in FIG. 4, the second sensor 34 detects the bar 32 and outputs an ON signal, and the first sensor 33 does not detect the bar 32. Outputs an OFF signal. The output signals of the first sensor 33 and the second sensor 34 are input to the control device 36 shown in FIG.

  In FIG. 5, when the output of the first sensor 33 is ON and the output of the second sensor 34 is OFF, the control device 36 does not drive the cylinder device 22 and puts the rod 24 in the contracted state. When the output of 33 is OFF and the output of the second sensor 34 is ON, the cylinder device 22 is driven to make the rod 24 extend.

  Next, the operation of the pallet lock device 10 and the pallet detection device 11 will be described with reference to FIGS. 6 and 7. FIG. 6 shows the unloading operation by the forklift, and FIG. 7 shows the unloading operation. 6 and 7, (a1), (b1), and (c1) show the operation of the pallet locking device 10, and (a2), (b2), and (c2) show the operation of the pallet detection device 11, respectively.

  In FIG. 6, (a1) and (a2) show the state when the fork 4 is inserted into the insertion hole P3 of the pallet P on the floor surface 40. At this time, the lock bar 20 is in a horizontal posture and is inserted into the insertion hole P3 together with the fork 4. The detection bar 32 is also in a horizontal posture, and is inserted into the insertion hole P3 together with the fork 4 and the lock bar 20. At this time, the first sensor 33 detects the detection bar 32 and outputs an ON signal, and the second sensor 34 outputs an OFF signal because the detection bar 32 is not detected.

  When the fork 4 is lifted from this state, the state shown in FIGS. 6B1 and 6B2 is obtained. The upper surface of the fork 4 contacts the lower surface of the upper deck board P2 of the pallet P. At the same time, the upper edge 20a of the lock bar 20 also contacts the lower surface of the upper deck board P2. At this time, the protrusion 32a of the detection bar 32 is pressed by the lower surface of the upper deck board P2 and moves downward, and the detection bar 32 turns clockwise in FIG. Accordingly, the first sensor 33 does not detect the detection bar 32 and outputs an OFF signal, and the second sensor 34 detects the detection bar 32 and outputs an ON signal.

  The control device 36 outputs a drive signal to the cylinder device 22 according to the change of the signals of the sensors 33 and 34, and turns the lock bar 20 in the clockwise direction as shown in (c1) of FIG. As a result, the front end of the lock bar 20 comes into contact with the upper surface of the lower deck board P2 of the pallet P, and the pallet P is fixed or locked to the fork 4 by pressing it. At this time, as shown in FIG. 6C2, the detection bar 32 maintains the same state as FIG. As the fork 4 continues to rise, the pallet P moves away from the floor surface 40 while maintaining the locked state, and is transported to another place by a forklift. At this time, the lock bar 20 elastically presses the lower deck board P2 by the action of the spring 30 as described above.

  In FIG. 7, (a1) and (a2) show a state immediately before the unloading is going to be performed. 7 (a1) and (a2) are the same as (c1) and (c2) in FIG. 6 described above, but are reprinted for easy understanding. At this time, the first sensor 33 does not detect the detection bar 32 and outputs an OFF signal, and the second sensor 34 detects the detection bar 32 and outputs an ON signal.

  When the fork 4 is lowered from this state, the state of (b1) and (b2) in FIG. 7 is obtained. When the pallet P is placed on the floor surface 40 and the lower deck board P2 comes into contact with the floor surface 40, the fork 4 is then separated from the lower surface of the upper deck board P1 of the pallet P. At the same time, the lock bar 20 turns upward slightly by receiving an upward force from the lower deck board P2. Further, the detection bar 32 turns in the counterclockwise direction of FIG. 7 by the force of the spring 35 and returns to the original horizontal posture. Thus, the first sensor 33 detects the detection bar 32 and outputs an ON signal, and the second sensor 34 outputs an OFF signal because the detection bar 32 is not detected.

  The control device 36 outputs a non-driving signal to the cylinder device 22 by reversing the signals of the sensors 33 and 34, and turns the lock bar 20 counterclockwise as shown in FIG. 7 (c1). As a result, the lock bar 20 is separated from the lower deck board P2 of the pallet P and returns to the original horizontal state. At this time, the detection bar 32 maintains the same state as in FIG. 7B2, as shown in FIG. In this way, the pallet P is unlocked, and the fork 4 can be freely detached from the pallet P, and unloading is completed.

  As described above, due to the action of the pallet detection device 11, the pallet locking device 10 performs an operation of locking the pallet P when the fork comes into contact with the upper deck board P1 of the pallet P. At the time of separation from the deck board P1, an operation of releasing the lock of the pallet P is performed. That is, the operations of locking and unlocking the pallet locking device 10 are all performed based on the contact and separation operations of the fork 4 and the upper deck board P1 of the pallet P. Therefore, since one pallet detection device 11 can detect both contact and separation between the pallet P and the floor surface 40, the pallet lock device 10 can be locked and unlocked together. In particular, the placement operation of the pallet P on the floor surface 40 is detected as the separation between the fork 4 and the upper deck board P1, and the unlocking operation of the pallet lock device 10 is executed based on this detection. Does not cause malfunction.

  The pallet lock device 10 can be locked immediately after the fork contacts the upper deck board P1 of the pallet P, or can be unlocked immediately after the fork is separated from the upper deck board P1 of the pallet P. . The pallet locking device 10 is locked when the fork approaches the upper deck board P1 of the pallet P to a predetermined distance or less, or unlocked when the fork is separated from the upper deck board P1 of the pallet P by a predetermined distance or more. An action can be performed. These can be freely selected and designed by appropriately changing the shape and arrangement of the detection bar 32 or the arrangement of the sensors 33 and 34. For example, the distance can be adjusted by increasing or decreasing the protrusion height of the protrusion 32 a of the detection bar 32 from the fork upper surface 4 a. As described above, if the fork is locked when the fork comes close to the upper deck board P1 by a predetermined distance, or if the fork is released when the fork is separated from the upper deck board P1 by a predetermined distance, a malfunction caused by vibration of the vehicle body is caused. Prevention is further ensured.

  Furthermore, the pallet locking device 10 is locked after a predetermined time has elapsed since the fork contacts the upper deck board of the pallet P, or a predetermined time has elapsed since the fork has separated from the upper deck board of the pallet P. The unlocking operation can be performed at a later time. This can be done freely by setting the control device 36 to perform appropriate delay control so that the cylinder device 22 is driven or not driven after a predetermined time has elapsed since the signals of the sensors 33 and 34 are received. Can design. As described above, the lock operation is performed when a predetermined time elapses after the fork contacts the upper deck board, or the lock release operation is performed when the predetermined time elapses after the fork is separated from the upper deck board. However, it is possible to reliably prevent malfunction due to vehicle body vibration.

  The pallet detection device 11 only needs to be able to detect the approach, separation, or relative distance between the fork 4 and the upper deck board P1 of the pallet P. Therefore, the configuration is not limited to the above-described embodiment, and various examples are conceivable. Can be. For example, a proximity sensor or the like that can directly detect the contact / separation or distance between the fork 4 and the upper deck board P1 may be used. It is not always necessary to provide two sensors 33 and 34, and the approach or separation between the fork 4 and the upper deck board P1 may be determined by turning on or off one of the sensors. As described above, the present invention can be modified in various ways, and the present invention includes all design examples as long as the gist thereof is not changed.

It is a perspective view of an order picking truck as an embodiment of the present invention. It is the figure which looked at the floor of the order picking truck as an embodiment of the present invention from the lower part. It is a vertical side view of the floor showing the configuration of the pallet lock device. It is a vertical side view of the floor showing the configuration of the pallet detection device. It is a block diagram which shows the circuit which controls operation | movement of a pallet lock apparatus. It is a model for demonstrating operation | movement at the time of unloading of a pallet lock apparatus and a pallet detection apparatus. It is a model for demonstrating the operation | movement at the time of unloading with a pallet lock apparatus and a pallet detection apparatus.

4 Fork 4a Top surface of fork 10 Pallet lock device (pallet lock means)
11 Pallet detection device (detection means)
20 Lock bar 21 Lock drive device (drive device)
P Pallet P1 Upper deck board P2 Lower deck board

Claims (1)

In a forklift having a fork inserted into a pallet for placing a load and lifting means for lifting and lowering the fork,
A lock bar that presses the upper surface of the lower deck board of the pallet; and a drive device that drives the lock bar; the lock bar presses the lower deck board of the pallet to lock the pallet; Pallet locking means for releasing the lock of the pallet when the pressed lock bar is separated from the lower deck board;
A detection bar that is supported so as to be pivotable up and down, normally maintains a horizontal state by the force of a spring, and in which the protrusion protrudes a predetermined dimension above the upper surface of the fork in the horizontal state; A first sensor for detecting the horizontal detection bar, and a first sensor for detecting the horizontal detection bar, and a protrusion of the detection bar as an upper deck of the pallet. A pallet detection device comprising: a second sensor that detects the swiveled detection bar by being pressed by the lower surface of the board and moving downward;
In response to the detection signal of the detection bar by the second sensor, the driving device of the pallet locking means is driven to lock the pallet with the lock bar, or the detection signal of the detection bar by the first sensor is received. A control device for driving the driving device of the pallet locking means to release the lock of the pallet by the lock bar,
When the fork inserted into the pallet is raised, the upper surface of the fork comes into contact with the lower surface of the upper deck board of the pallet, and at this time, the protrusion of the detection bar is pressed against the lower surface of the upper deck board of the pallet and moves downward. When the detection bar that has turned by moving is detected by the second sensor, the control device that has received the detection signal from the second sensor drives the drive device to lock the pallet,
Lowering the said fork inserted into the pallet, when the pallet is lowered still the fork is placed on a floor, the fork moves away from the lower surface of the upper deck board of the pallet, the force in this case the spring When the detection bar returned to the horizontal state by the first sensor is detected by the first sensor, the control device receiving the detection signal from the first sensor drives the drive device to unlock the pallet. A forklift characterized by that.

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