JP4278044B2 - Forklift pallet locking device - Google Patents

Description

  The present invention relates to a pallet locking device that is provided in a forklift and locks a pallet inserted into the fork.

  Conventionally, in a forklift in which an operator moves onto a pallet lifted from a loading surface by a fork such as an order picking truck and loads the load, the center of gravity of the load depends on the loading and unloading of the load and the position of the operator on the pallet. Since the position fluctuates, a pallet lock device for fixing the pallet supported by the fork to the fork is provided in order to prevent the pallet from tilting, skidding, or swinging due to the variation of the center of gravity of the load.

  Examples of the pallet locking device include those shown in the following patent documents, and as disclosed in patent documents 1, 2, and 3, a locking member using a space between the upper and lower deck boards of the pallet. The pallet is fixed by contacting the lower deck board or the upper and lower deck boards, or the pallet is fixed by contacting the lock member to the upper deck board of the pallet as disclosed in Patent Document 4. There is a configuration.

Since the load is loaded on the pallet, in the configuration in which the pallet is fixed only by the upper deck board, only the end of the upper deck board can be used for fixing the pallet. Therefore, in terms of stability for fixing the pallet, it can be said that the configuration in which the pallet is fixed by the upper and lower deck boards that can use the pallet size in the direction in which the fork is inserted is superior.
Japanese Patent Laid-Open No. 10-291790 Japanese Patent Laid-Open No. 11-228085 JP 2002-12397 A Japanese Patent Laid-Open No. 2001-316095

  All of the pallet locking devices described in these patent documents are manually operated, and forgetting the operation (locking operation and unlocking operation) cannot be solved. Therefore, the inventor of the present invention studied to automatically lock the pallet.

  When the structure which locks a pallet using an upper and lower deck board as mentioned above is employ | adopted, the double-sided pallet which has an upper and lower deck board can be conveyed without a problem. However, in the apparatus having this configuration, when a single-sided pallet having no lower deck board is mixed, the pallet locking operation is always performed on the single-sided pallet.

  When a pallet locking operation is performed when inserting a fork into a single-sided pallet, there is no lower deck board to which the locking member should come into contact, so the locking member protrudes below the lower end of the pallet, for example, the pallet In the case where the lock member is stored in a shelf or the like, there is a possibility that the protruding lock member may collide with the shelf and break the both.

  The present invention has been proposed from such a viewpoint, and an object of the present invention is to provide a device that can automate the pallet locking device instead of the conventional manual type and can sufficiently cope with the transportation of a single-sided pallet.

  The present invention employs the following means in order to achieve the above object. That is, the present invention provides a pallet detection means for detecting the presence or absence of a pallet on a fork, a lock bar for pressing the lower deck board of the pallet to lock the pallet, and the lock bar in the direction in which the pallet is locked or A driving machine that drives in the unlocking direction, and a driving limit detection means that detects whether the driving machine has driven the lock bar beyond the locking position to the driving limit when driving in the locking direction. And whether there is pressure contact between the lock bar and the lower deck board according to the elastic means interposed between the driving machine and the lock bar, and the amount of elastic deformation of the elastic means when driven in the locking direction. Lock detecting means for detecting, and detecting that the drive limit detecting means is driven to the drive limit in a state where the pallet detecting means detects the pallet. When, after returning to the release position by driving the lock bar in the release direction, the operation of holding the locking bar in the release position and configuration and control means for causing the said drive motor.

  According to the above configuration, when a double-sided pallet and a single-sided pallet are mixed, it is automatically determined whether or not the pallet to be transported is a single-sided pallet, and if it is a single-sided pallet, the lock bar is returned to the release position. Thus, the lock bar does not collide with the load shelf or the like because it is held at the release position.

  At this time, if the control means is configured to cause the driving machine to perform the operation of holding the lock bar in the release position until the pallet detection means detects that there is no pallet on the fork, Since the operation of holding the lock bar at the release position is completed when the conveyance is completed, the locking operation can be normally performed even if the double-sided pallet is subsequently conveyed.

  According to the present invention, the pallet locking device can be automated to prevent forgetting to lock when carrying a double-sided pallet, and when carrying a single-sided pallet, it is reliably determined that the pallet is a single-sided pallet and the lock bar is held in the release position. be able to.

  Further, since the operation according to the discrimination between the double-sided pallet and the single-sided pallet and the pallet type is automatically performed, the operator does not have to perform any troublesome operations related to the pallet lock.

  A pallet locking device for a forklift according to an embodiment of the present invention will be described in detail with reference to the drawings as follows. In the drawings, FIG. 1 is a side view of a pallet locking device for a forklift according to the present invention, and FIG. 2 is a plan view of the pallet locking device. FIG. 3 is a side view of an order picking truck provided with this pallet locking device.

  As shown in FIG. 3, this order picking truck is provided with a mast 4 at the rear of a vehicle body 3 that travels on a traveling surface by three wheels of a drive wheel 1 and left and right road wheels 2, and the mast 4 is raised and lowered. A cab 5 and left and right forks 6 supported in this manner are provided. In the present specification, the forward direction of the vehicle (the left direction in FIG. 3) is the front, and the vehicle width direction is described as the left and right with respect to the front direction.

  Corner pillars 7 are erected on the left and right corners of the front part of the cab 5, respectively, and a steering panel having a steering handle, a lift control operation switch, a travel control operation switch, etc. is supported at an intermediate height between both corner pillars 7. The head guard 8 is supported on the upper ends of the corner pillars 7. The deck 9 of the cab 5 is provided with a deadman type brake pedal, for example, and the left and right forks 6 are fixed to the lower surface of the cab 5.

  As shown in FIGS. 1 and 2, a pallet locking device 10 according to an embodiment of the present invention is provided below the deck 9 of the cab 5 between the left and right forks 6. Yes.

  The pallet locking device 10 includes a base plate 11 supported on the cab 5, a support shaft 13 supported on the rear end portion of the base plate 11 via left and right brackets 12, and a shaft supported by the support shaft 13. The left and right lock bars 14 are provided around the center, that is, around the left and right axial centers so as to be rotatable.

  Here, the left and right lock bars 14 are rotated around the support shaft 13 in a synchronized manner by connecting their intermediate portions to each other with a connecting frame 15.

  Further, the pallet locking device 10 is provided with driving means 16 for driving the left and right lock bars 14 in a direction for locking or releasing the pallet, and the driving means 16 has a front end portion via a left and right shaft 17. And a drive mechanism 18 comprising an electric cylinder or the like pivotally supported by the base plate 11 and an output portion of the drive mechanism 18, that is, a link mechanism 20 connected to the piston rod 19.

  FIG. 4 is a plan view of the link mechanism 20. As shown in FIGS. 1 and 4, the link mechanism 20 includes a first link arm having a lower end supported by the base plate 11 so as to be rotatable around a left and right axis, and an upper end connected to the piston rod 19. 21 and a lower end portion of the second link arm 22 that is supported by the base plate 11 so as to be rotatable around a left and right axis, and an intermediate portion or an upper end portion of the second link arm 22 that receives the connecting frame 15 from the front. And an excessive motion absorbing mechanism 23 that connects the upper part to the upper end of the second link arm 22.

  The excessive motion absorbing mechanism 23 includes a shaft 24 whose front end is connected to an intermediate portion of the first link arm 21 so as to be rotatable around a left and right axis, and a rear end of the shaft 24 is movable in the axial direction. The bracket 25 is connected to the upper end of the second link arm 22 so as to be rotatable about the left and right axis, and the bracket 25 is attached to the front end of the shaft 24 toward the rear end of the shaft 24. And an elastic means 26 made of an elastic body such as a compression coil spring to absorb excessive movement of the shaft 24 relative to the bracket 25.

  On the other hand, the lock bar 14 is urged in a direction (release direction) in which the connection frame 15 is pressed against the second link arm 22 by release urging means 27 that is stretched over the connection frame 15 and the base plate 11. Yes.

  As shown in FIG. 1, the lock bar 14 is formed in a bowl shape with a rounded rear end, and a pallet 40 (hereinafter referred to as a pallet 40 unless it is necessary to distinguish between both sides and one side). In a free state in which the release biasing means 27 and the driving means 16 are not mounted, the intermediate portion projects from the upper surface of the fork 6 and the lower surface is positioned horizontally at a position slightly higher than the lower surface of the fork 6. To be retained.

  FIG. 5 is a side view of the pallet locking device 10 in a state where the fork 6 inserted into the pallet 40 is raised to the pallet detection position where it abuts against the upper deck board 41.

  Since the urging force of the release urging means 27 is set to be weaker than the weight of the pallet 40, when the fork 6 rises to a height at which it abuts against the lower surface of the upper deck board 41, as shown in FIG. Is rotated in the direction of the lock position against the urging force of the release urging means 27 by the weight of the double-sided pallet 40.

  By the way, as shown in FIG. 1 and FIG. 4, a pallet detecting means 32 comprising, for example, a magnetic sensor for detecting that the lock bar 14 has moved below the upper surface of the fork 6 is provided on the base plate 11 via a bracket 42. It is supported.

  A driving piece 43 made of a magnet for driving the pallet detecting means 32 is supported by the lock bar 14 via the arm 44 and the connecting frame 15, and the highest part of the lock bar 14 is the upper surface of the fork 6 as shown in FIG. The drive piece 43 is separated from the pallet detection means 32 when the pallet detection means 32 is pushed down to the height of, for example, so that the pallet detection means 32 is switched from on to off, for example.

  As a result, the operation mode, which will be described in detail later, is switched from the free mode to the lock operation mode, the drive unit 18 is started, and the piston rod 19 is pushed backward. Then, after the second link arm 22 catches up and comes into contact with the connecting frame 15, the shaft 24 enters the bracket 25 (excessive operation), and the urging force of the elastic means 26 increases.

  Thus, when the biasing force of the elastic means 26 increases and overcomes the biasing force of the release biasing means 27 (shown in FIG. 7 described later as a position where the excessive operation amount X becomes the lower limit value A), the second link. The arm 22 drives the lock bar 14 via the connecting frame 15 toward the lock position (position where it abuts the lower deck board).

  However, the elastic means 26 may be incorporated at an appropriate built-in pressure so that the lock bar 14 is driven to the locked position without excessive operation. As shown in FIG. 4, the built-in height and built-in pressure of the elastic means 26 are set in the released state in which the driving machine 18 is shortened by the adjusting nut 28 screwed into the rear end portion of the shaft 24. The second link arm 22 is adjusted so as to receive the connecting frame 15 and restrain the lock bar 14 to the release position.

  FIG. 6 is a side view of the pallet locking device when the lock bar 14 is lowered to the locked position where it abuts against the lower deck board 46 of the double-sided pallet 40. As shown in FIG. 6, when the lock bar 14 is driven to the lock position, the lock bar 14, the connecting frame 15, and the second link arm 22 are restrained by the lower deck board 46. When the excessive operation amount X (shown in FIG. 7) of the link arm 21 and the shaft 24 with respect to the bracket 25 further increases. For example, when the excessive operation amount X reaches the upper limit value B, the lock bar 14 is applied to the lower deck board 46 with a predetermined pressure. Pressed to complete the lock.

  As shown in FIGS. 4 and 7, a locking nut 28a is screwed to the rear end portion of the shaft 24 to prevent loosening of the adjusting nut 28, and is held between the adjusting nut 28 and the locking nut 28a. The lock detecting means 31 is driven by the drive piece 29.

  As shown in FIG. 7, the lock detecting means 31 is composed of, for example, a potentiometer supported on the bracket 25 of the excessive motion absorbing mechanism 23 via a stay 35, and the tip of an arm 37 fixed to the input shaft 36 thereof. The excessive amount of operation X of the shaft 24 relative to the bracket 25 of the excessive operation absorbing mechanism 23 is detected by inserting a pin 38 provided in the U-shaped groove 39 formed in the drive piece 29.

  FIG. 8 is a side view of the pallet locking device 10 in a state where the pallet 40 is placed on the loading table and the fork 6 is separated from the upper deck board 41 by a predetermined distance or more. As shown in FIG. 8, when the pallet 40 is placed on the loading table and the fork 6 is separated from the upper deck board 41 by a predetermined distance or more, the bracket 25, the piston rod 19, the first link arm 21 and the shaft 24 are separated from each other. The second link arm 22, the connecting frame 15, and the lock bar 14 are excessively operated, and the excessive operation amount X is larger than the upper limit value B.

  When the pallet 40 is placed on the loading table and reaches a height at which the fork 6 and the lock bar 14 can be removed from the pallet 40 without hindrance, the excessive operation amount X becomes, for example, a predetermined value C. Then, the drive unit 18 is reversely operated to release the lock.

  FIG. 9 is a side view of the pallet locking device 10 in a state where the locking operation is performed when the one-side pallet 48 is supported by the fork 6 and the piston rod 19 has reached the drive limit position. FIG. 10 is a side view showing the state of the first link arm when the piston rod 19 is in the release position and the drive limit position.

  As shown in FIGS. 10 and 4, the base plate 11 is provided with a drive detecting means 33 made of, for example, a magnetic switch for detecting that the driving machine 18 is shortened and the piston rod 19 is located at the release position. Is supported through.

  The drive detection means 33 is turned on when the drive machine 18 is shortened and the piston rod 19 and the first link arm 21 are located at the release position where no drive is performed (shown in FIG. 10A). When the one link arm 21 rotates from the release position to the lock position with drive, the link arm 21 is switched off.

  The base plate 11 is supported by a drive limit detection means 34 made of, for example, a magnetic switch for detecting that the drive unit 18 is extended to the drive limit and the piston rod 19 is positioned at the drive limit position via a bracket 47. Has been.

  The drive limit detecting means 34 is turned on when the driving machine 18 is extended and the piston rod 19 and the first link arm 21 are located at the drive limit position (shown in FIG. 10B). When the link arm 21 rotates from the drive limit position toward the release position, the link arm 21 is switched off.

  In the above configuration, the operation of the pallet locking device when a double-sided pallet and a single-sided pallet are mixed will be described below.

  FIG. 11 is a functional block diagram of the control means 50 of this pallet locking device. As shown in FIG. 11, the control means 50 is supplied with output signals from the lock detection means 31, the pallet detection means 32, the drive detection means 33, and the drive limit detection means 34. Is provided with an abnormality detection means 51 for detecting the above, an operation mode setting means 52 for setting an operation mode to be described later according to the input value, and a drive machine control means 53 for controlling the drive machine 18 in accordance with the set operation mode.

  Further, the abnormality detecting means 51 is connected to a reporting means 60 such as a buzzer, chime, warning light, warning character display, etc., and informs the operator that an abnormality has occurred in the pallet lock device 10 and the contents of the abnormality. .

  FIG. 12 is a flowchart showing the control processing executed by the control means 50, which is repeatedly executed at an appropriate cycle after the main key of the order picking track is turned on and then turned off.

  First, an error check (S1) is performed by the abnormality detection means 51 to check whether there is an error in each part of the pallet lock device 10, and if it is confirmed that there is no error, the operation mode setting means 52 causes the drive machine to 18 operation modes are set (S2), and the drive machine control means 53 controls the drive machine 18 according to the mode setting result (S3).

  When an abnormality is detected in the error check (S1), the abnormality detection unit notifies the drive unit control unit 53 that the abnormality has been detected and stops driving the drive unit 18 (S4). The notification means 60 issues an alarm notifying the operator that there is an abnormality and the contents of the abnormality (S5).

  Here, the detected abnormality is, for example, when the lock detection means 31 detects a value of B or more as the excessive operation amount, the output value of the drive detection means 33 is on (the piston rod 19 is in the release position). .), Or when the output value of the pallet detection means 32 is on (no pallet), there is no consistency between the output values of the detection means.

  By the way, the operation mode of the driving machine 18 includes a free mode in which the lock bar 14 is held in the release position, a lock operation mode in which the lock bar 14 is driven from the release position to the lock position, and the lock bar 14 is held in the lock position. A lock mode and a release operation mode in which the lock bar 14 returns from the lock position to the release position. These operation modes are repeated in this order.

  FIG. 13 is a flowchart of the operation mode setting process (S2) performed by the operation mode setting means 52. As shown in FIG. 13, in the operation mode setting process (S2), it is first determined whether or not the drive detection means 33 is on (release position) (S31). It is determined whether or not a palette is detected by the palette detecting means 32 (S32).

  If it is determined that the pallet detection unit 32 is on (pallet non-detection), a single-sided pallet detection flag F, which will be described later, stored in the operation mode setting unit 52 is set to 0 (single-side pallet non-detection). It is reset (S33), and the operation mode is set to the free mode (S34). If it is determined that the pallet detection means 32 is off (pallet detection), it is determined whether or not the single-sided pallet detection flag F is 1 (single-sided pallet detection, see S40) (S35). At this time, if the one-side pallet detection flag F is 1, the operation mode is set to the free mode (S34), and if the one-side pallet detection flag F is 0, the operation mode is set to the lock operation mode ( S36).

  On the other hand, when it is determined that the drive detection means 33 is turned off in the on / off determination (S31), it is determined whether or not the operation mode is the lock operation mode (S37). Here, when it is determined that the operation mode is the lock operation mode, it is determined whether or not the lock is completed by determining whether or not the excessive operation amount X is B or more.

  That is, when the lock bar 14 comes into contact with the lower deck board 46 of the pallet 40 and the operation of the driving machine 18 is continued, the shaft 24 with respect to the lock bar 14, the connecting frame 15, the second link arm 22, and the bracket 25. Then, the first link arm 21 and the piston rod 19 are operated excessively, the elastic means 26 is shortened, and the pressure at which the lock bar 14 comes into contact with the lower deck board 46 increases. When the shortening amount of the elastic means 26, that is, the excessive operation amount X becomes, for example, the upper limit value B or more, the state in which the pallet 40 is sufficiently firmly fixed to the fork 6, that is, the locked state is completed. It can be determined whether or not the lock has been completed by determining whether or not (S38).

  On the other hand, when the pallet supported by the fork 6 is a single-sided pallet, the lock bar 14 is driven to the drive limit position while the excessive operation amount X remains A without being restrained at the lock position. At the drive limit position, the drive unit 18 reaches its stroke end and is restrained. In other words, the excessive operation amount X does not become B or more during single-sided pallet transportation.

  For this reason, in the determination of whether or not the excessive operation amount X is B or more (S38), if X <B, it is confirmed whether or not the drive limit detection means 34 is on (is in the drive limit position). (S39). If the drive limit detection means 34 is off, the lock bar 14 has not reached the lock position, so the operation mode is not changed and the lock operation mode is continued. On the contrary, if the drive limit detecting means 34 is on, the pallet supported by the fork 6 is a single-sided pallet without a lower deck board, so the single-sided pallet detection flag F stored in the operation mode setting means 52 is 1. (S40), and the operation mode is changed to the release operation mode (S41).

  Further, in the determination of whether or not the excessive operation amount X is B or more (S38), if the lock is completed, that is, if it is determined that X ≧ B, the operation mode is changed to the lock mode ( S42).

  When it is determined that the operation mode is the lock operation mode (S37), it is determined whether or not the operation mode is the lock mode (S43). If it is determined that there is a loading surface on which the pallet 40 is placed, that is, whether or not a rack is detected (S44), if it is determined that it is detected, the operation mode is changed to the release operation mode. The setting is changed (S45).

  In the rack detection determination (S43), the fork 6 with the pallet 40 placed on the loading surface is lowered to a predetermined pallet detection height, and the excessive operation amount X of the shaft 24 with respect to the bracket 25 becomes a predetermined value C or more. It is determined by whether or not it is.

  If it is determined in the determination (S43) whether or not the operation mode is the lock mode, the operation mode is set to the release operation mode, and the next drive unit control process is performed as it is. The process proceeds to (S3).

  As described above, when a single-sided pallet is detected and the single-sided pallet detection flag F is changed to 1, the drive detection means 33 is on (release position) and the pallet detection means 32 is not off (no pallet). As long as the single-sided pallet detection flag F is not changed to 0 (S31 → S32 → S33), the free mode is continued (S31 → S32 → S35 → S34). That is, the pallet lock device can be held in a state where the pallet is not locked.

  Next, the operation of the drive unit 18 in each operation mode will be described. FIG. 14 is a flowchart of the drive machine control process (S3). As shown in FIG. 14, in the drive machine control process, the drive machine control means 53 controls the drive machine 18 according to the mode set in the mode setting process (S2). First, the set operation mode is the free mode. (S51), if it is the free mode, it is determined from the control signal output to the drive unit 18 by the drive unit control means 53 whether or not the drive unit 18 is stopped. However, if it is stopped, the driving machine control process (S3) is terminated without doing anything.

  For example, when the drive unit 18 is not stopped in the free mode, such as immediately after the operation mode is switched from the release mode to the free mode (the drive unit 18 is operating but the piston rod 19 is in the release position). In this case, after the drive unit 18 is stopped (S53), the drive unit control process (S3) is terminated.

  In the determination of the free mode (S51), when it is determined that it is not the free mode, it is determined whether or not the operation mode is the lock operation mode (S54), and when it is determined that the operation mode is the lock operation mode. Determines whether or not the driving machine 18 is in operation (S55). If it is determined that the driving machine 18 is not in operation, the driving machine 18 is started to operate (S56) and then the driving machine is controlled. The process (S3) ends.

  In the determination of whether or not the operation mode is the lock operation mode (S54), if it is determined that the operation mode is not the lock operation mode, it is subsequently determined whether or not the operation mode is the lock mode (S57). Then, it is determined whether or not the driving machine 18 is stopped (S58), and if it is stopped, the driving machine control process (S3) is finished without doing anything.

  Immediately after switching from the lock operation mode to the lock mode, it may be determined that the drive unit 18 is operating. In this case, the driving machine 18 is stopped (S59), and the driving machine control process (S3) is terminated.

  If it is determined that the lock mode is not set (S57), since it is the release operation mode, it is determined whether or not the drive unit 18 is operating in reverse (S60). Otherwise, the reverse operation of the drive unit 18 is started (S61), and the drive unit control process (S3) is terminated.

  In the control process performed by the control means 50 repeated after the next time, when it is detected that the drive detection means 33 is switched on (release position) (S31), it is confirmed that no pallet is detected. (S32), the operation mode is set to the free mode (S34), and the reverse operation of the drive unit 18 is stopped (S51 → S52 → S53).

  As switches and sensors for the pallet detection means 32, drive detection means 33, drive limit detection means 34, etc., microswitches, proximity switches, magnetic sensors, photosensors, pressure switch potentiometers, encoders, and the like can be used.

  Moreover, although the case where the pallet locking device of the present invention is applied to an order picking truck has been described in the above embodiment, it can also be applied to other counterbalance type and reach type forklifts.

  The pallet locking device of the present invention can prevent forgetting to lock when carrying a double-sided pallet, and has the effect that the pallet locking device can hold the pallet without locking when carrying a single-sided pallet, which is useful for forklifts and the like. is there.

It is a side view of the present invention. It is a top view of the present invention. It is a side view of an order picking truck to which the present invention is applied. It is a top view of the link mechanism of this invention. It is a side view at the time of the palette detection of this invention. It is a side view in the lock operation mode of this invention. It is a side view of the excessive operation | movement absorption mechanism of this invention. It is a side view at the time of rack detection of this invention. It is a side view at the time of the single-sided pallet detection of this invention. It is a side view which shows the 1st link arm of the cancellation | release position and drive limit position of this invention. It is a functional block diagram of the control means of this invention. It is a flowchart of the control processing of this invention. It is a flowchart of the operation mode setting process of this invention. It is a flowchart of the drive machine control processing of this invention.

Explanation of symbols

6 fork 14 lock bar 16 drive means 31 lock detection means 32 pallet detection means 33 drive detection means 34 drive limit detection means 40 pallet 46 lower deck board 50 control means

Claims (2)

Pallet detection means for detecting the presence or absence of a pallet on the fork;
A lock bar that locks the pallet by pressing the lower deck board of the pallet;
A drive unit for driving the lock bar in a direction to lock the pallet or to release the lock;
Drive limit detection means for detecting whether the drive has driven the lock bar to the drive limit beyond the lock position when driven in the locking direction;
Elastic means interposed between the driving machine and the lock bar;
Lock detecting means for detecting the presence or absence of pressure contact between the lock bar and the lower deck board based on the amount of elastic deformation of the elastic means when driven in the locking direction;
When the pallet detection means detects that the drive limit detection means has driven to the drive limit while detecting the pallet, the lock bar is driven in the release direction and returned to the release position, and then the lock bar is Control means for causing the driving machine to perform the operation of holding the release position;
A pallet locking device for a forklift, comprising: 2. The control device according to claim 1, wherein the control unit causes the driving machine to perform an operation of holding the lock bar in a release position until the pallet detection unit detects that there is no pallet on the fork. Forklift pallet locking device.

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