JP2006103926A - Forklift truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems in reach type and counterbalance type forklift trucks wherein a vehicle speed is relatively high and a pallet may slide on a fork when a vehicle body is abruptly stopped or abruptly turned. <P>SOLUTION: This forklift truck 1 comprises a pallet lock means 5 for fixing the pallet P supported on the fork 4 to the fork 4 and a control means 32 for controlling the operation of the pallet lock means 5. Moreover, the forklift truck comprises a first sensor S1 as a pallet detection means detecting the presence or absence of the pallet P supported on the fork 4 and a second sensor S2 as a traveling state detection means detecting the traveling state of the forklift truck 1. The control means 32 controls the pallet lock means 5 based on outputs from the first sensor S1 and the second sensor S2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a forklift, and more particularly to a forklift provided with a device for locking a pallet inserted in the fork so that the pallet does not swing or slide.

  The pallet locking device is often used in a forklift generally called an order picking truck that allows an operator to perform a picking operation on a pallet inserted into a fork. In this order picking truck, if the pallet swings during the picking work, there is a risk that the operator may cause a fall accident. Therefore, it is very important to suppress the swing of the pallet by the pallet locking device. An example in which the pallet locking device is applied to an order picking track is described in Patent Document 1 below. In the invention of this Patent Document 1, in order to prevent an operator from falling down, a configuration is adopted in which the pallet is locked when the pallet, that is, the fork reaches a predetermined height or more.

Such a pallet locking device can prevent the pallet from sliding on the fork, and also has the effect of preventing the collapse of the load. Therefore, other than the order picking truck, the side of the vehicle body such as the reach type or the counter balance type The application is also expanding to forklifts with driver seats. An example in which the pallet locking device is applied to a reach-type forklift is described in Patent Document 2 below. In the invention of Patent Document 2, a switch that is manually operated by an operator is provided in the driver's seat on the vehicle body side, and the operation of the pallet lock device or the release of the operation is controlled by this switch.
Japanese Patent Laid-Open No. 2003-112896 JP 2003-182959 A

  In the reach type and counterbalance type forklifts described above, the operator does not perform the picking work on the pallet unlike the order picking truck, but the vehicle speed is faster than the order picking truck, so the forklift body stops suddenly or turns sharply. As a result, the possibility that the pallet slides on the fork is great. However, as in the invention of Patent Document 2, if the operation or release of the pallet locking device is performed by an operator's manual operation, if the operation is forgotten, the pallet may slide to cause collapse of the load.

  The present invention pays attention to such circumstances, and an object of the present invention is to provide a forklift that can reliably prevent the pallet from sliding even when the pallet locking device is applied to the reach type or counterbalance type forklift. To do.

  In order to achieve the above object, as a first invention, a pallet locking means for fixing a pallet supported by the fork to the fork and a control means for controlling the operation of the pallet locking means are provided. A forklift comprising a traveling state detecting means for detecting a traveling state of the forklift, wherein the control means controls the pallet locking means based on an output of the traveling state detecting means. .

  As a second invention, there is provided the forklift according to the first invention, wherein the control means locks the pallet by the pallet locking means when the vehicle speed of the forklift is higher than a predetermined value.

  As a third invention, there is provided a forklift according to the first invention, wherein the control means releases the lock of the pallet by the pallet lock means when the vehicle speed of the forklift is lower than a predetermined value. To do.

  As a fourth invention, in the first invention, the control means operates the pallet locking means to lock the pallet when the vehicle speed of the forklift is higher than a predetermined value, and when the vehicle speed is lower than the predetermined value, the pallet Provided is a forklift characterized in that the lock means is deactivated to unlock the pallet.

  As a fifth invention, in the first invention, the control means shifts the pallet lock means from the unlocked state to the locked state when the vehicle speed of the forklift becomes greater than a first predetermined value, The pallet locking means is shifted from the locked state to the unlocked state when the value becomes smaller than a predetermined value of 2, and the first predetermined value is set to a value larger than the second predetermined value. A forklift is provided.

  According to a sixth aspect of the present invention, there is provided a forklift comprising a pallet lock means for fixing a pallet supported by the fork to the fork and a control means for controlling the operation of the pallet lock means, Pallet detection means for detecting the presence or absence of a supported pallet; and travel state detection means for detecting the travel state of the forklift; and the control means is based on outputs of the pallet detection means and the travel state detection means. A forklift is provided that controls the pallet locking means.

  As a seventh invention, in the sixth invention, when the pallet is supported on the fork and the vehicle speed of the forklift is higher than a predetermined value, the control means locks the pallet with the pallet locking means. A forklift is provided.

  As an eighth invention, in the sixth or seventh invention, when the pallet is not supported by the fork, the control means controls the pallet by the pallet locking means regardless of the vehicle speed of the forklift. Provided is a forklift that is unlocked.

  As a ninth invention, there is provided a forklift according to the first to eighth inventions, wherein the forklift is a reach type or counterbalance type forklift.

  According to the forklift according to the first aspect of the invention, the control means for controlling the operation of the pallet locking means automatically performs the operation of the pallet locking means, that is, the locking operation or the unlocking operation based on the traveling state of the forklift. Therefore, the problem that the pallet slides on the fork during a sudden stop or a sudden turn can be surely solved.

  According to the forklift according to the second aspect of the invention, the pallet is locked when the vehicle speed of the forklift is higher than a predetermined value. Therefore, when there is a possibility of sudden stop or sudden turn, the pallet is surely slid. There is an effect that can be prevented.

  Further, according to the forklift according to the third invention, since the pallet is unlocked when the vehicle speed of the forklift is smaller than a predetermined value, the useless locking operation when there is little possibility of sudden stop or sudden turn. Is eliminated, and the power of the pallet locking means can be reduced.

  Further, according to the forklift according to the fourth invention, the pallet is locked when the vehicle speed of the forklift is higher than a predetermined value, and is unlocked when the vehicle speed is lower than the predetermined value. Or the lock can be released.

  According to the forklift according to the fifth aspect of the invention, the first predetermined value as the reference value for locking the pallet is set larger than the second predetermined value as the reference value for releasing the lock. As a result, the operation of locking and unlocking is not repeated too frequently, the operation of the pallet locking means is stabilized, and it is possible to reliably prevent the sliding of the pallet.

  According to the forklift according to the sixth aspect of the invention, since the operation of the pallet locking means is controlled based on the presence / absence of the pallet supported by the fork and the traveling state of the forklift, it is determined whether or not the pallet exists on the fork. It is possible to lock the pallet after confirmation, and therefore, there is an effect that the operation of the pallet locking means can be surely performed without waste.

  According to the forklift according to the seventh aspect of the invention, since the pallet is supported by the fork and the pallet is locked when the vehicle speed of the forklift is higher than a predetermined value, the pallet on the fork is reliably slid. There is an effect that it can be prevented.

  Further, according to the forklift according to the eighth aspect of the invention, when the pallet is not supported by the fork, the pallet is unlocked regardless of the vehicle speed of the forklift. The power of the pallet lock means can be saved.

  According to the forklift according to the ninth aspect of the invention, it is possible to realize control of the pallet locking means suitable for the reach type or counterbalance type forklift.

  As shown in FIG. 1, a forklift 1 according to an embodiment of the present invention has a lift bracket 2 as load support means for supporting a load W, and a lifting device 3 for lifting and lowering the lift bracket 2. Yes. The lift bracket 2 includes a pair of left and right forks 4 that support the load W via the pallet P, and a pallet locking device 5 as pallet locking means for fixing the pallet P to the fork 4. The elevating device 3 includes a pair of left and right masts 6 standing on the vehicle body for guiding the lift bracket 2 in the vertical direction, a lift cylinder 7 elevating the lift bracket 2 along the mast 6, A drive source (not shown) for supplying pressure oil to the cylinder 7 is provided. The forklift 1 according to the present embodiment exemplifies a reach-type forklift in which the lifting device 3 can move in the front-rear direction of the vehicle body, that is, in the left-right direction in FIG.

  As shown in FIG. 2, the lift bracket 2 includes a guide roller (not shown) for sliding with respect to the mast 6, a tilt shaft 8 provided horizontally in the vehicle body left-right direction, that is, the vehicle width direction, and the tilt shaft 8 Are mainly composed of a pair of tilt cylinders 9 and a tilt bracket 10 whose upper end is rotatably supported by the tilt shaft 8. As shown in FIG. 2, the tilt bracket 10 includes a pair of upper and lower plate-shaped bearing portions 11 that are rotatably connected to the tilt shaft 8, and a tilt bar 12 that is installed between the bearing portions 11. Consists mainly of. A backrest 13 for supporting a load W on the pallet P supported by the fork 4 is integrally fixed to the upper portion of the tilt bracket 10.

  When the tilt cylinder 9 is driven and its cylinder rod 14 protrudes to the front side of the vehicle body, that is, the front side of the sheet of FIG. 2, the rod 14 presses the tilt bracket 10 toward the front of the vehicle body. The vertical portion 4a is pressed forward of the vehicle body. Therefore, the tilt bracket 10, the backrest 13 and the fork 4 are simultaneously turned by the same angle around the tilt shaft 8. When the tilt cylinder 9 is not driven, the cylinder rod 14 is shortened, and the tilt bracket 10, the backrest 11 and the fork 4 are restored to their original positions shown in FIG.

  Next, the configuration of the pallet lock device 5 will be described with reference to FIGS. The pallet lock device 5 includes a pair of lock bars 15 installed so as to be parallel to the horizontal portion 4 b of the fork 4 and one lock drive installed vertically so as to be parallel to the vertical portion 4 a of the fork 4. The device 16 is a main component, and the lock bar 15 and the lock drive device 16 are formed so as to be substantially L-shaped as viewed from the side.

  The lock bar 15 is a plate-like object disposed close to the inside of each of the forks 4 and 4, with a support shaft 17 provided on the vehicle rear side, that is, the base end side of the lock bar 15 as a center. It turns so that the front-end | tip part of a vehicle body front side may move up and down. As shown in FIG. 2, the support shaft 17 is fixed to the lower end of the tilt bar 12 and fixed between two suspension blocks 18 and 18 extending downward. The lock bar 15 is disposed so as to be parallel to the horizontal portion 4b of the fork 4 in the normal state, ie, the non-operating state shown in FIG. Therefore, when the fork 4 is inserted into the insertion hole of the pallet P, these two lock bars 15 are also inserted simultaneously.

  Support plates 19, 19 extending inwardly are fixed to each lock bar 15, and both support plates 19 are connected and fixed to a single left and right long connection plate 21 by bolts 20. A plurality of screw holes 22 are formed in the connecting plate 21 along the longitudinal direction thereof. Depending on which screw hole 22 is inserted into the bolt 20 and the support plate 19 and the connecting plate 21 are fastened, both screw holes 22 are formed. The interval between the lock bars 15, 15 can be adjusted freely.

  The lock driving device 16 has a long cylindrical lock cylinder 23 arranged in the vertical direction. The electric or hydraulic lock cylinder 23 is suspended at an upper end thereof by a tilt shaft 8 provided on the lift bracket 2 via an appropriate bracket so that the cylinder rod 24 can be vertically moved from the lower end. It expands and contracts. The front end or lower end of the cylinder rod 24 is connected to an inverted U-shaped U-shaped block 26 via a spring 25, and the U-shaped block 26 is positioned above the connecting plate 21 and has a square shape 2 as viewed from the side. A single pivot link 27 is pivotally connected, and the lower end of the link 27 is pivotally coupled to the support shaft 17.

  When the lock cylinder 23 is driven and the cylinder rod 24 extends, the U-shaped block 26 presses the connecting plate 21 downward via the spring 25. As a result, the lock bar 15 turns about a predetermined angle about the support shaft 17 from the horizontal posture shown in FIG. At this time, the swing link 27 pivots by a predetermined angle in the clockwise direction in FIG. 4 about the support shaft 17, and the lock cylinder 23, spring 25, and U-shaped block 26 are slightly centered about the tilt shaft 8. Turn counterclockwise. A return spring 28 shown in FIG. 3 is stretched between the connecting plate 21 and the tilt bar 12. When the lock cylinder 23 is not driven and the cylinder rod 24 is shortened, the spring 28 The connecting plate 21 is pulled upward by the force, and the lock bar 15 returns to the horizontal posture shown in FIG. 4 and comes into contact with a stopper (not shown) and stops.

  As described above, when the tilt cylinder 9 is driven and the cylinder rod 14 protrudes toward the front side of the vehicle body, the tilt bracket 10, the backrest 13 and the fork 4 turn around the tilt shaft 8. Since the support shaft 17 fixed to the bracket 10 also turns, the above-described pallet lock device 5 also turns in the same direction by the same angle as these.

  The lock drive device 16 is covered with a box-shaped protective cover 29 in the front and left and right directions of the vehicle body, and the load W on the pallet P abuts against the lock drive device 16 and dust from the load W is collected. It is possible to prevent the adhesion and prevent the occurrence of a failure.

  Next, a device for driving and controlling the pallet lock device 5 will be described. In the cover 29, a photoelectric reflection type first sensor S1 is disposed as a pallet detecting means together with the lock driving device 16. The first sensor S1 is fixed to the tilt bar 12 via a bracket (not shown), and can detect whether or not the pallet P is inserted into the fork 4 and the lock bar 15 as shown in FIG. In order to be able to do so, it is supported in a diagonally forward and downward posture. The protective cover 29 is formed with a window 30 for transmitting the light beam from the first sensor S1. As shown in FIG. 1, in the vicinity of one front wheel 31 of the forklift 1, a second sensor S <b> 2 is disposed as a traveling state detection means for detecting the rotational speed of the front wheel 31.

  In FIG. 5, the output signals from the first sensor S1 and the second sensor S2 are transmitted to a control circuit 32 including a microcomputer as control means installed in the forklift vehicle body, and output from the control circuit 32. The signal is sent to the lock cylinder 23 through a drive circuit 33 installed inside the vehicle body.

  Next, the pallet locking operation by the pallet locking device 5 will be described with reference to FIGS. First, as shown in FIG. 6A, the fork 4 is inserted into the insertion hole of the pallet P placed on the rack or floor L. At this time, since the first sensor S1 does not detect the pallet P and the traveling speed of the forklift vehicle detected by the second sensor S2 is also slow, the lock bar 15 is in a horizontal posture parallel to the horizontal portion 4b of the fork 4. It is in. FIG. 6B shows a state where the fork 4 is completely inserted into the insertion hole of the pallet P and the lock bar 15 is also inserted at the same time as the fork 4 and then the fork is lifted to lift the pallet P. Yes. At this time, the first sensor S1 detects the pallet P as shown in step ST1 of FIG. As a result, the control circuit 32 starts calculating the number of revolutions per unit time, that is, the traveling speed of the vehicle body, from the output of the second sensor S2. After that, the forklift starts traveling with the pallet P lifted, and when the traveling speed becomes higher than the predetermined speed as shown in step ST2 of FIG. 7, the control circuit 32 sends a lock signal to the drive circuit 33 as shown in step ST3 of FIG. Send. Along with this, the drive circuit 33 drives the lock cylinder 23 of the lock drive device 16 and turns the lock bar 15 as shown in FIG. 6C to press the upper surface of the lower deck board P2 of the pallet P. At this time, the pallet P is pressed upward on the lower surface of the upper deck board P1 by the upper surface of the horizontal portion 4b of the fork 4, and is pressed downward on the upper surface of the lower deck board P2 by the lock bar 15. On the other hand, it is in a locked state that does not slide easily.

  Thereafter, when the vehicle speed becomes smaller than the predetermined value as shown in step ST4 of FIG. 7, the control circuit 32 transmits an unlock signal to the drive circuit 33 as shown in step ST5 of FIG. 7 by the output of the second sensor S2. Along with this, the drive circuit 33 deactivates the lock cylinder 23 of the lock drive device 16 and returns the lock bar 15 to the state shown in FIG.

  The predetermined traveling speed described above is set to a speed at which the pallet P may slide on the fork 4 due to traveling of the vehicle body. When the pallet P is made of resin, it is more slippery than when it is made of wood, so the predetermined traveling speed is set to be relatively small. In addition, when the forklift is used in a refrigerator, ice easily adheres to the pallet P and the fork 4. In this case as well, it is preferable to set the predetermined traveling speed smaller than in other places of use. When the pallet P is very slippery, the predetermined traveling speed is set to zero or a value close to zero, and the pallet P is locked if the vehicle body is traveling even a little in step ST2 of FIG. If the vehicle body stops in step ST4 of FIG. 7, the pallet P can be unlocked.

  According to the embodiment described above, the lock operation and unlock operation of the pallet P can be performed according to changes in the vehicle speed, and thus the pallet P slides on the fork 4 during a sudden stop or a sudden turn. Can be surely prevented. In addition, since the above-described locking and unlocking can be automatically performed, the pallet P does not slide unexpectedly due to forgetting the operation or the like. Furthermore, since the pallet P can be locked only when the pallet P is likely to slide, a useless locking operation can be eliminated. Moreover, in the above-described embodiment, the presence or absence of the pallet P supported by the fork 4 is detected by the first sensor S1, and the locking operation is executed only when the pallet P exists. Save more

  Note that the predetermined vehicle speed in step ST2 in FIG. 7 and the predetermined vehicle speed in step ST4 in FIG. 7 are different from each other in order to prevent the locking operation and the unlocking operation from being repeated too frequently according to the change in vehicle speed. It can also be set to a value. That is, if the vehicle speed in step ST2 is set to 20 km / h and the vehicle speed in step ST4 is set to 15 km / h, the number of lock operations and unlock operations can be reduced by the action of hysteresis. Alternatively, when the state greater than the predetermined vehicle speed continues for a predetermined time in step ST2 of FIG. 7, the process proceeds to step ST3 of the same figure for the first time, and when the state lower than the predetermined vehicle speed continues for the predetermined time in step ST4 of FIG. Even if it moves to step ST5 of the figure for the first time, it can suppress that locking operation and unlocking operation are repeated too frequently according to the change of vehicle speed.

  In the embodiment described above, both the pallet locking operation and the unlocking operation are controlled according to the vehicle speed. However, only the locking operation is controlled according to the vehicle speed, and the unlocking operation is controlled by the manual operation of the operator. It is also possible to use other means. For example, a switch for detecting the raising / lowering operation of the fork can be provided, and the unlocking operation can be performed when the fork is lowered by a predetermined distance or when the fork is lowered to a predetermined ground height. Similarly, it is possible to use other means such as controlling the locking operation manually by the operator, and to control only the unlocking operation according to the vehicle speed as in the above embodiment. For example, a switch for detecting the raising / lowering operation of the fork can be provided, and the locking operation can be performed when the fork is raised by a predetermined distance or when the fork is raised to a predetermined ground height.

  In the above-described embodiment, the pallet locking or unlocking operation is controlled according to the vehicle speed. However, the acceleration of the forklift vehicle body or the state of the vehicle turning angle or the like is detected, and the vehicle travels. It is also possible to control the locking operation or the unlocking operation based on whether the acceleration, the angular velocity of turning the vehicle body, or the angular acceleration is larger or smaller than a predetermined value. Therefore, the running state in this specification means not only the running speed of the vehicle body but also the running acceleration, angular velocity, angular acceleration, etc. of the vehicle body.

  Further, in the above-described embodiment, the first sensor S1 is a photoelectric reflection type sensor, but a contact type sensor may be used instead. The second sensor S2 detects the rotational speed of the front wheel 31 of the vehicle body. However, the second sensor S2 may detect not only the front wheel but also the rotational speed of the rear wheel. Further, the second sensor S2 does not directly detect the number of rotations of the wheel, but detects whether or not the operator has operated a switch for instructing traveling of the vehicle body, or the operation amount is more than a predetermined value. It is also possible to detect the vehicle speed indirectly by detecting whether the speed is large or small.

  As described above, the present invention is not limited to the embodiments described in the specification, and various design changes are possible. Therefore, the present invention includes various forms without departing from the spirit of the present invention. As described above, the present invention is suitable for reach-type or counterbalance-type forklifts. However, the present invention is not limited thereto, and can be applied to order picking trucks, and includes application examples to various forklifts. .

The side view which shows the forklift which concerns on embodiment of this invention. The front view which shows a lift bracket. The front view of a pallet locking device. The side view of a pallet locking device. The block diagram which shows the circuit for control and drive of a pallet locking device. The schematic diagram explaining operation | movement of a pallet lock apparatus. The flowchart which shows operation | movement of a pallet lock apparatus.

Explanation of symbols

1: Car body 4: Fork 5: Pallet lock device (pallet lock means)
15: Lock bar 16: Lock drive device 32: Control circuit (control means)
P: Pallet S1: First sensor (pallet detection means)
S2: Second sensor (running state detection means)
W: Load

Claims (9)

  A forklift provided with a pallet locking means for fixing a pallet supported by the fork to the fork and a control means for controlling the operation of the pallet locking means, wherein the running state detects the running state of the forklift A forklift comprising a detecting means, wherein the control means controls the pallet locking means based on an output of the traveling state detecting means.   2. The forklift according to claim 1, wherein the control means causes the pallet lock means to lock the pallet when the vehicle speed of the forklift is higher than a predetermined value.   2. The forklift according to claim 1, wherein when the vehicle speed of the forklift is smaller than a predetermined value, the control unit releases the lock of the pallet by the pallet lock unit.   The control means activates the pallet locking means to lock the pallet when the vehicle speed of the forklift is larger than a predetermined value, and releases the pallet lock by deactivating the pallet locking means when the vehicle speed is smaller than the predetermined value. The forklift according to claim 1 characterized by things.   The control means shifts the pallet locking means from the unlocked state to the locked state when the vehicle speed of the forklift exceeds a first predetermined value, and the pallet locking means when the vehicle speed becomes lower than the second predetermined value. The forklift according to claim 1, wherein the first predetermined value is set to be larger than the second predetermined value.   A forklift comprising a pallet lock means for fixing a pallet supported by the fork to the fork and a control means for controlling the operation of the pallet lock means, wherein the presence or absence of the pallet supported by the fork is determined. Pallet detecting means for detecting, and traveling state detecting means for detecting the traveling state of the forklift, wherein the control means controls the pallet locking means based on outputs of the pallet detecting means and the traveling state detecting means. A forklift characterized by that.   7. The forklift according to claim 6, wherein the control means locks the pallet by the pallet locking means when the pallet is supported by the fork and the vehicle speed of the forklift is higher than a predetermined value. .   8. The control device according to claim 6 or 7, wherein when the pallet is not supported by the fork, the pallet locking device releases the lock of the pallet regardless of the vehicle speed of the forklift. A forklift according to any one of the above.   The forklift according to any one of claims 1 to 8, wherein the forklift is a reach type or a counterbalance type forklift.

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