JP2006168855A - Forklift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forklift capable of surely locking or unlocking a pallet in response to a distance between the pallet and a pallet loading surface when lifting and lowering the pallet. <P>SOLUTION: In this forklift 1, a distance between a load supporting device 2 and a pallet loading surface 10 to be loaded with the pallet 4 is detected by a detecting device 8, and a pallet lock device 6 is operated to lock or unlock on the basis of an output of the detecting device 8. Furthermore, the forklift 1 can determine existence of the pallet 4 by detecting whether a pallet detecting means is brought in contact with the pallet 4 or not, an expensive proximity sensor and wiring for the same is unnecessary. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a forklift that can lock or open a pallet supported by a fork in a timely manner.

It is preferable that the pallet locking device automatically performs a locking operation when the fork lifts the pallet and automatically releases the lock when the fork lowers the pallet onto the shelf or the ground. Such an apparatus is described in the following patent document.
JP 2003-40594 A JP 2003-252598 A JP 2003-252595 A

Patent Document 1 discloses a technique for performing locking or unlocking operation when a dog is fixed at a predetermined height position of a mast that guides raising and lowering of a fork, and a pallet locking device moves up and down together with the fork and comes into contact with the dog. is doing. But this device lifts the pallet from the ground,
Or although it can respond | correspond to the operation | work which lowers | hangs the pallet to the ground, there exists a problem that it cannot use for the lifting of the pallet from the shelf etc. whose height is not constant, or the operation | work of lowering the pallet.

Patent Documents 2 and 3 lock the pallet when lifting or lowering the pallet from any shelf or ground (pallet placement surface) without causing the above problems. Or it can be unlocked.

Patent Document 2 discloses a technique for controlling the operation of the pallet locking device based on the vertical positional relationship of the fork with respect to the pallet. In other words, if the fork comes close to the upper deck board of the pallet, it will be regarded as "I'm trying to lift the pallet" and perform a locking operation.
If the fork is close to the lower deck board of the pallet, "I'm trying to lower the pallet"
It is considered that the lock is released.

Patent Document 3 states that if the fork is raised to a predetermined height on the condition that the insertion of the fork into the pallet is detected, the “pallet lifting operation is performed”.
A technique for performing the locking operation on the basis of the above is disclosed.

Further, in the techniques disclosed in Patent Documents 2 and 3, the operation is performed without knowing the height of the “pallet placement surface” for lifting and lowering the pallet, and the pallet is actually removed from the pallet placement surface. Without confirming whether it was lifted or whether the work of lowering to the pallet placement surface was performed, it was locked based on the positional relationship between the fork and the pallet and assuming that the work was performed. An unlocking operation is performed.

Therefore, the devices according to Patent Documents 2 and 3 may cause malfunction due to vibrations of the vehicle body or pallet during traveling. For example, in the device according to Patent Document 2, the pallet is vibrated up and down with respect to the fork, and can be locked or unlocked without permission. Further, in the apparatus according to Patent Document 3, it may be erroneously detected that the pallet is inserted due to vibration of the vehicle body, and the lock may be arbitrarily performed by the subsequent raising of the fork. Both problems are caused by trying to control the operation of the lock by estimation or assumption without actually confirming the operation of lifting or lowering the pallet from the mounting surface.

A specific example of a technique for detecting a pallet is described in Patent Document 2. That is, when the slope is raised at the top edge of the lock bar, and the lock bar enters into the hole of the pallet together with the fork, the slope comes into sliding contact with the upper deck board of the pallet. The tilted posture is slightly lowered. When the lock bar takes this posture, a magnet provided at an appropriate position of the lock bar is detected by a proximity sensor or the like.

However, the proximity sensor must be accurately positioned so that the magnet provided on the lock bar in the inclined posture as described above and the proximity sensor face each other reliably. In addition, when a foreign substance such as dust adheres to the proximity sensor, the proximity sensor may malfunction. In addition, it is not desirable to add an expensive proximity sensor from the viewpoint of reducing the manufacturing cost, and there is a problem that more labor is required for manufacturing the forklift because it requires complicated wiring work to attach it to the forklift. .

Therefore, the present invention can securely lock or unlock the pallet regardless of the height of the pallet placement surface when lifting or lowering the pallet, and the above-described conventional problems are solved. An object is to provide a forklift that does not occur.

The present invention includes a load support means for supporting a load, and an elevating means for raising and lowering the load support means, wherein the load support means supports the load via a pallet, A forklift having a pallet locking device for fixing a pallet to the fork, and moving up and down together with the load supporting means, detecting a distance to a detected object in a detection area having directivity, and sending an output signal The detecting means and the detecting means take a first posture in which a pallet placement surface for placing the pallet is placed in the detection area, or a second posture in which the pallet placement surface is removed from the detection area, The biasing hand is brought into contact with the pallet supported by the fork, a biasing means for holding the detection means in the second posture, a biasing means for supporting the sensing means in a movable manner, and the fork. Based on the output signal of the detection means, the pallet detection member that sets the detection means to the first posture against the detection position, the fixed member that is arranged corresponding to the detection area of the detection means that takes the second posture, and And a control device for operating or releasing the operation of the pallet locking device.

The present invention also includes load support means for supporting a load, and lifting means for lifting the load support means, the load support means supporting the load via a pallet; A forklift provided with a detecting means for raising and lowering together with the load supporting means, detecting a distance to a detected object in a detection area having directivity, and sending an output signal; and the detecting means,
Support for movably supporting the detection means so as to take a first posture in which a pallet placement surface for placing the pallet is placed in the detection area, or a second posture in which the pallet placement surface is removed from the detection area. A body, an urging means for holding the detecting means in the second posture, and the pallet supported by the fork, thereby contacting the urging means with the detecting means in the first posture. A pallet detection member to be fixed, a pallet lock device for pressing the pallet detection member against the pallet to fix the pallet to the fork, and a fixing arranged corresponding to the detection area of the detection means taking the second posture A member and a control device for operating or releasing the operation of the pallet locking device based on an output signal of the detection means.

Further, the control device sets a predetermined height as a lock height, and the pallet lock device is controlled based on the fact that the distance between the load support means and the pallet placement surface has reached the lock height or more. The pallet locking device is released based on the fact that the distance is less than the lock height.

Furthermore, the forklift according to the present invention is characterized by comprising a fixing member arranged corresponding to a detection area of the detection means taking the second posture. Further, the fixing member is disposed at a distance less than the lock height from the detection means taking the second posture.

Furthermore, the detection means measures the distance between the load support means and the pallet placement surface with ultrasonic waves or laser beams oscillated from the load support means to the pallet placement surface. .

Further, the detection means is an ultrasonic displacement sensor attached to the load support means and capable of obtaining an output proportional to a change in the distance between the load support means and the pallet placement surface.

According to the forklift according to the present invention, when the pallet is in contact with the pallet while the pallet is supported by the fork, the member makes the detection means in the first posture against the urging means. As a result, the pallet placement surface enters the detection area of the detection means having directivity as the detected object, so that the detection means detects the distance from the load support means to the pallet placement surface while moving up and down together with the load support means. To do. Based on the output signal of the detection means, the control device can operate or release the pallet locking device, so that the operator does not have to manually operate the pallet locking device, reducing the burden on the operator associated with cargo handling work. can do.

Further, even when the pallet placement surface (for example, “shelf”) is provided at various heights such as a rack shelf, according to the forklift, the load supporting means is raised by the elevating means. When the pallet supported by the pallet is raised to a predetermined distance (height) from the pallet placement surface, the pallet locking device performs the pallet locking operation. Therefore, installation of a sensor or dog that detects the height of the pallet corresponding to the height of the pallet placement surface in advance as in the prior art,
And these adjustments are unnecessary.

Furthermore, the pallet locking device is operated based on the fact that the distance from the load supporting means detected by the detecting means to the pallet placement surface reaches or exceeds the predetermined lock height, and the same distance is the same as the lock height. If the control device is configured so as to release the pallet locking device based on the fact that the pallet mounting surface is not satisfied, the above-described effect can be achieved even when the pallet placement surface changes to various heights. In addition, when changing the height at which the pallet locking operation is performed, the pallet height is not detected by a sensor or dog as in the prior art, so it is simply performed by changing the set value of the lock height. be able to.

In the forklift according to the present invention, the pallet does not come into contact with the pallet detection member in an empty state in which nothing is supported by the fork. Therefore, the detection means is held in the second posture by the urging means. For this reason, although the pallet placement surface deviates from the detection area of the detection means, since the fixing member enters the detection area of the detection means as the detection object, the detection means detects the distance to the fixing member. In this state, since the fixing member is arranged at a distance less than the lock height from the detection means, the control device does not operate the pallet locking device.

Therefore, the pallet locking device does not operate wastefully in an empty state. This is a particularly beneficial effect for eliminating the waste of the storage battery and maintaining the output of the storage battery for a long time when the forklift has a specification in which the storage battery is mounted as a main power source.

As described above, since the forklift changes the attitude of the detection means according to the mechanical operation of the pallet detection member, it is more expensive than the case where the presence or absence of the pallet is determined based on the output of the proximity sensor or the like. No additional wiring and associated wiring work is required. Therefore,
The manufacturing cost of the forklift can be greatly reduced. In addition, when changing the height at which the pallet locking operation is performed, the pallet height is not detected by a sensor or dog as in the prior art, so it is simply performed by changing the setting value of the lock height. be able to.

Furthermore, the forklift according to the present invention is a non-contact type sensor in which the detecting means measures the distance with ultrasonic waves or laser beams, so that the presence or absence of the pallet placement surface or the load is applied regardless of the material of the pallet placement surface. There is an advantage that the distance from the support means to the pallet placement surface can be detected. For example, when an ultrasonic switch is applied to the detection means, it is easy to attach it to the load support means. Further, the ultrasonic switch has an advantage that it can be easily added to an existing forklift or the like. Alternatively, when an ultrasonic displacement sensor is applied to the detection means, the control device can recognize a more accurate distance based on this output.

As shown in FIGS. 1 and 2, a forklift 1 according to an embodiment of the present invention includes a load support device 2 that is an example of a load support unit that supports a load, and an elevating unit that lifts and lowers the load support device 2. An elevating device 3 as an example, and the load supporting device 2 is configured so that the load supporting device 2 supports the load via the pallet 4 and the pallet locking device 6 configured to be able to fix the pallet 4 to the fork 5 in a timely manner.
With.

The elevating device 3 is a mast 31 that guides the load supporting device 2 that is a lift bracket so as to be movable up and down.
And a lift cylinder 32 that raises and lowers the load supporting device 2 or holds it at a desired height.
The fork 5 is supported by the load supporting device 2 in a posture in which the rear end is bent upward to form an upright portion 51 and the tip 52 protrudes forward. Details will be described in the following examples.

The pallet lock device 6 includes a control device 7 having a CPU as a main body, a detection device 8 that is an example of a detection means for detecting a distance to a detected object in a detection area having directivity, and a lifting device 3 that makes the pallet 4 A recording device 11 that records a predetermined height H rising from the pallet placement surface 10 such as a floor surface as a lock height, and a lock mechanism 12 that operates according to a command signal from the control device 7.
With.

A known technique can be applied as the lock mechanism 12. For example, the lock mechanism 12 moves the lock bar R together with the fork 5 into the hole of the pallet 4 and presses the lock bar R against the lower deck board of the pallet 4, thereby fixing the pallet 4 to the fork 5. The pallet 4 can be unlocked by separating R from the lower deck board.

The detection device 8 is attached to the location indicated by the symbol X as shown in FIG. Detection device 8
For example, a non-contact sensor that measures the distance to the object to be detected with an ultrasonic wave or a laser beam can be applied. In this case, regardless of the material of the object to be detected, the detection device 8 has the presence or absence of the pallet placement surface 10,
Alternatively, the distance from the load support device 2 to the pallet placement surface 10 can be reliably detected. The “detection area” corresponds to a range in which ultrasonic waves or laser beams are oscillated from the measurement end of the detection device 8.

Next, the mounting structure of the detection device 8 will be described in detail. As shown in FIG. 3A, a pair of pins 81 and 82 are fixed to a base plate 80 fixed to a side surface near the rear end of the fork 5 so as to be separated from each other, and a sleeve rotatably supported by one pin 81 is provided. 83, the support 84 is joined,
The detection device 8 is fixed to the L-shaped end portion 85 of the support body 84. The other pin 82 is the sleeve 9
1 is rotatably supported, and a pallet detection member 9 having a tip 92 extending forward of the fork 5 is joined to a sleeve 91. Between the other pin 82 and the sleeve 91, a torsion spring 93 that urges the pallet detection member 9 in the counterclockwise direction indicated by the arrow CCW in the drawing.
Since the pallet detection member 9 is in an empty state in which nothing is supported by the fork 5,
The front end 92 is flipped up higher than the fork 5, and the rear end 94 is abutted against the support body 84.

In addition, a torsion spring 86 is provided between one pin 81 and the sleeve 83 to urge the support body 84 in the counterclockwise direction. The torsion spring 86 is more elastic than the torsion spring 93. Since the force is weak, the support body 84 maintains the second posture together with the detection device 8 while the upper end 87 thereof is in pressure contact with the lower surface near the rear end 94 of the pallet detection member 9. Thus, in the detection area of the detection device 8 taking the second posture, a fixing member 88 made of a plate material fixed at an appropriate position of the load support device 2.
Enters.

In the state shown in FIG. 3A, when the pallet detection member 9 enters the hole of the pallet 4 together with the fork 5 in order to support the pallet 4 on the fork 5, in this process, the vicinity of the tip 92 of the pallet detection member 9 is moved. By slidingly contacting the upper deck board of the pallet 4, the tip 92 of the pallet detection member 9 is pushed down. In other words, the pallet detection member 9 is connected to the torsion spring 9.
3 turns counterclockwise as indicated by the arrow CW in the figure, and assumes the posture shown in FIG. Along with this, the support 84 is allowed to turn counterclockwise by the torsion spring 86, so that the support 84 is in the first posture together with the detection device 8.

Thus, since the pallet mounting surface 10 positioned directly below the detection device 8 enters the detection area of the detection device 8 taking the first posture, the detection device 8 moves up and down together with the load support device 2 while supporting the load. The distance from the apparatus 2 to the pallet placement surface 10 is detected and an output signal is sent out. Based on this output signal, the control device 7 operates the pallet lock device 6 as follows or cancels the operation. This will be described in correspondence with S1 to S3 in FIG.

First, when the operator performs the cargo handling work by operating the forklift 1, as shown in FIGS. 1, 2, and 5A, the forklift 1 is moved forward while the fork 5 is lowered, and the pallet is placed. A fork 5 is inserted into the pallet 4 placed on the surface 10. In this state, when the operator operates the lever or the like at the driver's seat of the forklift 1 to extend the lift cylinder 32, the load supporting device 2 is raised accordingly. On the other hand, the control device 7 compares the distance A that is continuously output as the output signal from the detection device 8 with the above-described lock height H (S1). That is, since the lock height H is recorded in the recording device 11 as a preset height (reference distance), the control device 7 determines that the reference distance and the load supporting device 2 are actually from the pallet placement surface 10. Compare the raised height.

If the distance A is smaller than the lock height H (A <H) even when the load supporting device 2 is lifted from the pallet placement surface 10, the lock mechanism 12 moves the lock bar R to the lower deck board of the pallet 4. (S2). Then, as shown in FIG. 5B, when the distance A reaches the lock height H (A = H), the control device 7 operates the lock mechanism 12 to fix the pallet 4 to the fork 5. (S3). Although the load supporting device 2 may be further raised, as shown in FIG. 5C, after the distance A becomes equal to or higher than the lock height H (A ≧ H), the lock mechanism 12 fixes the pallet 4. To maintain.

On the other hand, as shown in FIG. 5C, in order to lower the pallet 4 onto the pallet placement surface 10 from the state where the pallet 4 is fixed by the lock mechanism 12 (S3), the operator must By operating the lever or the like, the lift cylinder 32 is shortened. Accordingly, the load supporting device 2 is lowered. On the other hand, the control device 7 compares the distance A continuously output from the detection device 8 with the lock height H recorded in the recording device 11 (S1).

Even when the load supporting device 2 descends toward the pallet placement surface 10, if the distance A is equal to or higher than the lock height H (A ≧ H), the lock mechanism 12 maintains the pallet 4 fixed (S3). And
As shown in FIG. 5A, when the distance A becomes smaller than the lock height H (A <H), the control device 7 releases the fixation of the pallet 4 by the lock mechanism 12 (S2). The load supporting device 2 further descends and returns to the position shown in FIG. When the distance A becomes smaller than the lock height H in this way, the lock mechanism 12 keeps the lock bar R away from the lower deck board of the pallet 4. Therefore, after placing the pallet 4 on the pallet placement surface 10, the operator can extract the fork 5 from the pallet 4 by moving the forklift 1 backward.

The operation of the lock mechanism 12 by the control device 7 as described above can be realized even when the pallet placement surface 10 is not a floor surface, as shown in FIGS. For example, when the pallet 4 raised from the floor through the steps S1 to S3 is transferred to the rack shelf 13, as shown by the solid line in FIG. Alternatively, it is raised to a position higher than the bottom plate 14. Then, when the forklift 1 is approached toward the rack shelf 13 and the detection device 8 reaches just above the bottom plate 14, the control device 7 recognizes the bottom plate 14 as the pallet placement surface 10 and sets the distance A to the lock height. Compared with H (S1).

In this state, if the distance A is smaller than the lock height H (A <H), the control device 7 immediately releases the fixation of the pallet 4 by the lock mechanism 12 (S2). Alternatively, the control device 7 is connected to the bottom plate 1
When 4 is recognized as the pallet placement surface 10, if the distance A is greater than or equal to the lock height H (A ≧ H), the lock mechanism 12 maintains the pallet 4 fixed (S3), but the operator supports the load. When the device 2 is lowered and the distance A becomes smaller than the lock height H (A <H), the control device 7 releases the fixation of the pallet 4 by the lock mechanism 12 (S2). Therefore, the operator can remove the fork 5 from the pallet 4 by lowering the load supporting device 2 and placing the pallet 4 on the bottom plate 14 and then retracting the forklift 1.

Further, also when the pallet 4 is put in and out of the lower stage of the rack shelf 13 shown in FIG. 6, the control device 7 recognizes the lower base plate 15 as the pallet placement surface 10. Thus, even if the pallet placement surface 10 changes to various heights, according to the forklift 1, the load support device 2 is lifted by the lifting device 3 and the pallet 4 supported by the fork 5 is placed on the pallet. When the pallet lock device 6 rises from the surface 10 to a predetermined height, the pallet 4 is locked.

Accordingly, it is not necessary to install a sensor or a dog for detecting the height of the pallet 4 corresponding to the height of the pallet placing surface 10 in advance and to adjust these. Further, the distance A may be set or changed arbitrarily. In this case, this can be done simply by rewriting the set value of the lock height H recorded in the recording device 11.

Further, as described above, since the detection device 8 is held in the second posture in an empty state in which nothing is supported by the fork 5, as shown in FIG. 7, the pallet placement surface is detected from the detection area of the detection device 8. 10 is removed, and the detection device 8 cannot detect the distance A. However, since the fixing member 88 enters the detection area of the detection device 8 as a detection target, the detection device 8 detects the distance to the fixing member 88.
In this state, since the fixing member 88 is disposed at a distance B that is less than the lock height H with respect to the detection device 8 (B <H), the control is performed even if the detection device 8 detects the distance B. The device 7 does not operate the pallet lock device 6 (S2). Therefore, if it is in an empty load state, the pallet lock device 6 will not operate wastefully regardless of the distance from the load support device 2 to the pallet placement surface 10.

As described above, the distances A and B are detected by the detection device 8, and the control device 7 operates the pallet lock device 6 or releases the operation in a timely manner based on the output of the detection device 8. Since it is not necessary for the operator to manually perform the operation 6, it is possible to prevent forgetting the operation or release work of the pallet lock device 6, and to reduce the burden on the operator accompanying the cargo handling work.

In addition, since the posture of the detection device 8 is changed according to the mechanical operation of the pallet detection member 9 so that the presence or absence of the pallet 4 can be determined depending on whether or not the pallet detection member 9 is in contact with the pallet 4, the presence or absence of the pallet 4 is determined. Compared with the case of making a determination based on the output of a proximity sensor or the like, it is not necessary to add an expensive proximity sensor and the wiring work associated therewith.

When the detection device 8 is attached to a reach-type forklift, the lower portion of the tilt bar 18 adjacent to the upright portion 51 of the fork 5 can be used as a fixing member 88 as shown in FIG.

As shown in FIG. 9A, the pallet locking device 60 applied to the forklift according to the present embodiment is different from the configuration of the first embodiment in that a fluid pressure cylinder 61 arranged in the vicinity of the upright portion 51 of the fork 5 is used. Thus, the pallet detection member 90 is directly operated. That is, the fluid pressure cylinder 61 is mainly a hydraulic or pneumatic cylinder attached near the lower end of the load supporting device 2. Although not shown, the hydraulic cylinder 61 is connected to a hydraulic pump or a compressor. The hydraulic pump or compressor supplies hydraulic pressure or air pressure to the fluid pressure cylinder 61 based on a command signal from the control device 7, so that the operating rod 62 moves forward and backward with respect to the fork 5.

The operation of the forklift according to the present embodiment will be described. Hereinafter, the same reference numerals are given to the components described above, and detailed illustration or description thereof will be omitted. Further, the operation steps of the control device 7 and the distances A and B will be described with reference to FIGS.

First, when the fork 5 is inserted into the pallet 4 placed on the pallet placing surface 10 based on the operation of the operator, in this process, as shown in FIG. Near the sliding contact with the upper deck board of the pallet 4. As a result, the tip 92 of the pallet detection member 90 is pushed down against the elastic force of the torsion spring 93, and the pallet detection member 9.
0 is a posture represented by a virtual line in the figure. Along with this, the support 84 is allowed to turn counterclockwise by the torsion spring 86, so that the support 84 is in the first posture together with the detection device 8.

Subsequently, in the process in which the load supporting device 2 is lifted together with the pallet 4, the step (S1) in which the control device 7 compares the distance A output from the first posture detecting device 8 with the lock height H is already performed. As described above. In addition, when the distance A is smaller than the lock height H (A <H), the step (S2) in which the lock mechanism 12 stands by with the lock bar R separated from the lower deck board of the pallet 4 is also described. It is as follows.

When the load supporting device 2 is further raised and the distance A is equal to or higher than the lock height H (A ≧ H), the control device 7 advances the operating rod 62 of the fluid pressure cylinder 61 in the direction indicated by the arrow F. As a result, the actuating rod 62 pushes the rear end 94 of the pallet detection member 90 forward, so that the pallet detection member 90 pivots around the other pin 82 in the clockwise direction, and the pallet detection member 9.
The zero tip 92 is pressed against the lower deck board of the pallet 4. In this state, pallet 4
Can be fixed to the fork 5 (S3).

Further, as shown in FIG. 9B, if the tip 92 of the pallet detection member 90 is bifurcated, the number of places where the lower deck board of the pallet 4 is pressed can be increased. In addition, although one fluid pressure cylinder 61 and one pallet detection member 90 constituting the pallet locking device 60 are shown in the drawing, the forklift 1 includes two or more forks 5, so that each fork 5 has a pallet. Each of the locking devices 60 is preferably provided.

On the contrary, when the pallet 4 is lowered onto the pallet placing surface 10 from the state where the pallet 4 is fixed to the fork 5 (S3), when the distance A becomes smaller than the lock height H in the process of lowering the load supporting device 2 ( A <H), the control device 7 retracts the operating rod 62 of the fluid pressure cylinder 61. As a result, the actuating rod 62 moves away from the rear end 94 of the pallet detection member 90, so that the pallet detection member 90 pivots around the other pin 82 counterclockwise as described above, and the tip 92 of the pallet detection member 90 is the pallet. 4 separates from the lower deck board (S2).

Further, the tip 92 of the pallet detection member 9 jumps higher than the fork 5 in an empty state in which nothing is supported by the fork 5, and the detection device 8 taking the second posture in this state detects the distance to the fixing member 88. The points to do are as described above. Therefore, in an empty state, the pallet lock device 6 does not operate wastefully regardless of the distance from the load support device 2 to the pallet placement surface 10.

It should be noted that the present invention can be implemented in a mode in which various improvements, modifications, or variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention. For example, the detection device 8 is not limited as long as it can measure the distance between the load support device 2 and the pallet placement surface 10 or detect whether or not this distance has reached a predetermined height. For example, a relatively small and lightweight ultrasonic switch may be applied. The control device 7 can be configured with only the ON / OFF signal output from the ultrasonic switch.
Can discriminate between A ≧ H and A, B <H.

The present invention can lock the pallet that has entered the fork with the pallet locking device, so that the pallet is stably supported by the fork and is useful for preventing inadvertent load collapse.

The side view of the forklift which concerns on embodiment of this invention. The block diagram which shows the structure of the control apparatus applied to the forklift which concerns on Example 1 of this invention. (A) The side view which shows the principal part of the forklift which concerns on Example 1 of this invention, (b) is a perspective view which shows the operation example. The flowchart explaining operation | movement of the forklift which concerns on Example 1 of this invention. The side view explaining an example of operation | movement of the forklift which concerns on Example 1 of this invention in order of (a) thru | or (c). The side view explaining other examples of operation of a forklift concerning Example 1 of the present invention in order of (a) thru / or (c). The side view explaining the operation example at the time of empty loading of the forklift which concerns on Example 1 of this invention. The perspective view of the modification of the load support apparatus applied to the forklift which concerns on Example 1 of this invention. (A) The side view which shows the principal part of the forklift which concerns on Example 2 of this invention, (b) is a perspective view of the pallet detection member.

Explanation of symbols

1: Forklift 2: Load support device 3: Lifting device 4: Pallet 5: Fork 6, 60: Pallet lock device 7: Control device 8: Detection device 9: Pallet detection member 10, 14, 15: Pallet placement surface

Claims (7)

A load supporting means for supporting the load; and a lifting / lowering means for raising and lowering the load supporting means, wherein the load supporting means supports the load via the pallet; A forklift with a pallet locking device fixed to
Detection means for raising and lowering together with the load supporting means, detecting a distance to a detected object in a detection area having directivity, and sending an output signal;
The detection means includes a first pallet placement surface on which the pallet is placed in the detection area.
A support that movably supports the detection means so as to take a second posture in which the pallet placement surface is removed from the posture or the detection area;
Biasing means for holding the detection means in the second posture;
A pallet detection member that brings the detection means into the first posture against the urging means by contacting the pallet supported by the fork;
A forklift comprising: a control device for operating or releasing the operation of the pallet locking device based on an output signal of the detection means. A forklift having a load support means for supporting a load and a lifting means for raising and lowering the load support means, the load support means including a fork for supporting the load via a pallet; ,
Detection means for raising and lowering together with the load supporting means, detecting a distance to a detected object in a detection area having directivity, and sending an output signal;
The detection means includes a first pallet placement surface on which the pallet is placed in the detection area.
A support that movably supports the detection means so as to take a second posture in which the pallet placement surface is removed from the posture or the detection area;
Biasing means for holding the detection means in the second posture;
A pallet detection member that brings the detection means into the first posture against the urging means by contacting the pallet supported by the fork;
A pallet locking device that presses the pallet detection member against the pallet to fix the pallet to the fork;
A forklift comprising: a control device for operating or releasing the operation of the pallet locking device based on an output signal of the detection means. The control device sets a predetermined height as a lock height, and operates the pallet lock device based on the fact that the distance between the load supporting means and the pallet placement surface has reached the lock height or more. The forklift according to claim 1 or 2, wherein the pallet locking device is released based on the fact that the distance is less than the lock height. The forklift according to claim 3, further comprising a fixing member arranged corresponding to a detection area of the detection means taking the second posture. 5. The forklift according to claim 4, wherein the fixing member is disposed at a distance less than the lock height from a detection unit that takes the second posture. The said detection means measures the distance of the said load support means and the said pallet mounting surface with the ultrasonic wave or laser beam oscillated from the said load support means to the said pallet mounting surface. The forklift according to any one of 1 to 5. 2. The ultrasonic displacement sensor, wherein the detection means is an ultrasonic displacement sensor attached to the load support means and capable of obtaining an output proportional to a change in the distance between the load support means and the pallet placement surface. The forklift as described in any one of thru | or 6.

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