JP3627978B2 - Cargo handling vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cargo handling vehicle such as a forklift.
[0002]
[Prior art]
Generally, as a forklift for performing loading and unloading operations at a high lift position, for example, there is a reach type forklift.
[0003]
As shown in FIG. 4 , this type of reach-type forklift is provided with a drive tire 2 and caster tire 3 on the rear part of the vehicle body 1 on which an operator rides, and a pair of straddles from the front part of the vehicle body 1. The arm 4 extends horizontally toward the front, and a road tire 5 is disposed at the tip position of each straddle arm 4. Further, a mast 8 for elevating (lifting) the fork 7 is erected on the inner position of each straddle arm 4.
[0004]
Then, the fork 7 is moved up and down together with the mast 8 using the lift hydraulic cylinder 10 erected along the mast 8 as an actuator, and the mast 8 is operated using the reach hydraulic cylinder 11 built in the vehicle body 1 as an actuator. It is moved back and forth along the straddle arm 4.
[0005]
Further, the fork 7 is attached to a lift bracket 12 provided on the mast 8 so as to be movable up and down via a support shaft 13, and a tilt hydraulic cylinder 14 fixed to the lift bracket 12 is used as an actuator for the fork 7. Is tilted.
[0006]
A traveling motor 16 is disposed inside the vehicle body 1, and the drive tire 2 is rotationally driven by the traveling motor 16, and accordingly, the vehicle body 1 moves forward and backward and turns. .
[0007]
Further, the vehicle body 1 is provided with a controller 17. The controller 17 is composed of a microcomputer or the like, and comprehensively controls the operation of each device and the cooperative operation of various devices.
[0008]
An operation panel 18 is secured at the driver's seat where the operator gets in, and a plurality of operation levers 20 for operating the hydraulic cylinders 10, 11, and 14 are arranged on the operation panel 18.
[0009]
For example, when unloading the load 6 placed on the rack shelf 21 using such a reach-type forklift, first, the operation lever 20 is operated, and the fork 7 is placed on the load 6. After raising to the height, the load 6 is scooped up from the rack shelf 21 with the fork 7, and then the fork 7 is moved back together with the mast 8 and then the fork 7 is lowered.
[0010]
In this loading operation, if the fork 7 suddenly contacts the rack shelf 21, there will be inconveniences such as collapse of the load, so that the fork 7 on which the load 6 is placed completely goes out of the rack shelf 21. The fork 7 needs to be moved backward as it is, so that the fork 7 is not lowered during that time.
[0011]
[Problems to be solved by the invention]
By the way, when such a conventional reach type forklift is used to take out the load 6 placed at a height higher than a certain height of the rack shelf 21, the following inconvenience occurs. ing.
[0012]
When the position of the fork 7 inserted into the rack shelf 21 is high, the fork 7 is located at a long distance from the operator's viewpoint, so the mast 8 interposed between the rack shelf 21 and the operator, etc. Becomes an obstacle and the operator's view is obstructed, making it difficult to visually recognize the state of the load 6 palletized on the fork 7. Moreover, since the rack shelf 21 is often installed in a dim warehouse, it is very difficult to visually recognize that the fork 7 has gone out of the rack shelf 21.
[0013]
As described above, conventionally, since it is difficult to visually recognize the positional relationship between the fork 7 and the rack shelf 21, the operator has not yet completely come out of the rack shelf 21 in practice. When the fork 7 has left the rack shelf 21, the fork 7 may start to descend. As a result, the fork 7 comes into contact with the rack shelf 21 and tilts greatly, and as a result, load collapse has occurred.
[0014]
Although the above description relates to the reach type forklift, other problems can be pointed out similarly to various forklifts for loading and unloading the load 6 such as a counter balance type, a picking type, and a straddle type.
[0015]
The present invention was devised in view of such inconveniences, and due to an operator's misjudgment when loading and unloading the load, the fork during the lowering operation unexpectedly contacts the rack shelf and causes the collapse of the load. An object of the present invention is to provide a forklift that can effectively prevent the occurrence of such problems.
[0016]
[Means for Solving the Problems]
A forklift according to claim 1 of the present invention is a forklift provided with a fork for placing a load on a vehicle body and a lifting device for driving the fork up and down along the mast. Tilt detection means that is supported on the vehicle body in a tiltable manner and that detects tilting of the fork is provided, and when the tilt detection means detects that the fork is tilted more than a predetermined angle. Lowering prohibiting means for prohibiting the lowering operation of the fork by the lifting device is provided .
[0017]
A forklift according to a second aspect of the present invention includes the configuration of the first aspect of the present invention, wherein the forklift is provided with a tilting drive means for tiltingly driving the fork with respect to a vehicle body, and the tilt detecting means is The fork lowering operation by the elevating device is prohibited when the fork tilting not based on the tilt driving means is detected .
[0018]
A forklift according to a third aspect of the present invention includes the configuration according to the first or second aspect, further comprising a lift height detecting means for detecting a lift height of the fork by the lifting device, and the lowering prohibition The means is characterized in that the lowering of the fork is prohibited on the condition that the lifting height of the fork detected by the lifting height detecting means is not less than a predetermined value set in advance .
[0019]
A forklift according to a fourth aspect of the present invention includes the configuration of the first to third aspects of the invention, and when the tilt detection means detects that the fork is tilted more than a predetermined angle, A vehicle body stop means for stopping the vehicle body from moving forward and backward is provided .
[0020]
Reach forklift according to claim 5 of the present invention, claims 1 in those containing the structure of the fourth aspect invention, when the fork by the tilting detecting means is detected that tilts more than a predetermined angle Comprises a reporting means for reporting that the vehicle is in a descending danger state .
[0021]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention applied to a reach type forklift will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a main part of a control system provided in the reach-type forklift according to this embodiment. Since the overall structure of the reach type forklift according to the present embodiment is not fundamentally different from the conventional form shown in FIG. 4 , the overall structure of the reach type forklift will be described with reference to FIG .
[0022]
In the reach type forklift of this embodiment, a drive tire 2 and a caster tire 3 are disposed at the rear part of the vehicle body 1, and a pair of straddle arms 4 are formed horizontally from the front part of the vehicle body 1 toward the front. It is extended to. A road tire 5 is disposed at the tip position of each straddle arm 4, and a mast 8 that guides the lifting and lowering operation of the fork 7 is erected at an inner position of each straddle arm 4.
[0023]
Further, the fork 7 and the mast 8 are moved up and down by a lifting device 31 having a hydraulic cylinder 10 standing along the mast 8 and by a reach device 32 having a hydraulic cylinder 11 built in the vehicle body 1. It is configured to move back and forth while being guided by the straddle arm 4.
[0024]
The height position of the fork 7 that has been moved up and down is detected by a reel-type potentiometer connected to the fork 7 via a wire, or a lift height detection means 33 such as a magnet sensor.
[0025]
Further, as shown in FIG. 2, the fork 7 is attached to a lift bracket 12 provided on the mast 8 so as to be movable up and down via a support shaft 13, and the lift bracket 12 has a tilt hydraulic pressure. The cylinder 14 is fixed. Further, a tilt bar 36 is tiltably attached to the support shaft 13 of the lift bracket 12 so as to be interposed between the fork 7 and the hydraulic cylinder 14. The fork 7 is pressed through a tilt bar 36 and tilted.
[0026]
The tilt bar 36 attached to both ends of the support shaft 13 has a proximity sensor 37 for projecting and receiving light, and the light from the photoelectric proximity sensor 37 is reflected on the side of the fork 7 facing the lift bracket 12. The proximity sensor 37 and the reflection pin 38 constitute a tilt detection means 39 that detects the tilt of the fork 7 .
[0027]
As shown in FIG. 2B, when the fork 7 is unexpectedly tilted due to the fork 7 being hooked on the rack shelf 21 or the like, the reflecting pin 38 moves from the light projecting / receiving range by the proximity sensor 37 as the fork 7 tilts. Therefore, the light from the proximity sensor 37 is not reflected by the reflection pin 38, and the reflected light is not incident on the proximity sensor 37, thereby detecting that the fork 7 is tilted more than a predetermined angle. Further, when the hydraulic cylinder 14 which is a tilt driving means is driven, the fork 7 tilts together with the tilt bar 34, so that the reflection pin 38 does not deviate from the light projecting / receiving range by the proximity sensor 37. Tilt detection by the tilt detection means 39 is not performed.
[0028]
In FIG. 2, reference numeral 41 denotes a backrest attached to the upper portion of the lift bracket 12, and reference numeral 42 denotes a guide roller that guides the lift bracket 12 along the mast 8 together with the fork 7.
[0029]
A traveling motor 16 is disposed inside the vehicle body 1, and the drive tire 2 is rotationally driven by the traveling motor 16, and accordingly, the vehicle body 1 moves forward and backward and turns. .
[0030]
The operation panel 18 provided in the operator's driver seat is provided with a plurality of operation levers 20 for moving the fork 7 up and down, tilting, and moving the mast 8 back and forth, as well as lamps and buzzers. A notification means 45 such as a liquid crystal display is arranged. Further, the operation panel 18 is provided with a manual lowering prohibition release switch 46 for canceling a lowering prohibition operation based on an operation of an arithmetic processing unit 17a of the controller 17 described later.
[0031]
On the other hand, the operator's foot position in the driver's seat is an electromagnetic brake or the like, together with a pedal brake that stops the traveling operation by the traveling device 5 and an accelerator that increases the rotational speed of the traveling motor 16 (both not shown). A vehicle body stopping means 47 configured is arranged.
[0032]
Furthermore, inside the vehicle body 1, there is disposed a controller 17 composed of a microcomputer or the like for comprehensively controlling the operation of each device and the coordinated operation of various devices. And a memory unit 17b composed of a ROM, a RAM, or the like that stores various types of data.
[0033]
And the arithmetic processing part 17a is comprised so that the function as a fall prohibition means in a claim may be exhibited. For this reason, each signal is input to the arithmetic processing unit 17a from each of the tilt detection unit 39, the elevation detection unit 33, and the lowering prohibition release switch 46, and the elevator unit 31, Signals instructing these operations are output to each of the reach device 32, the tilt drive means 14, the notification means 45, and the vehicle body stop means 47.
[0034]
Next, the control operation at the time of the load taking operation performed by the reach type forklift according to this embodiment will be described with reference to the flowchart shown in FIG. S means each step.
[0035]
First, after the operator of the reach-type forklift turns on a key switch (not shown) on the operation panel 18 to activate the forklift (S1), the controller 17 operates the operation levers 20 so that the controller 17 Various operation processes are executed according to (S2). That is, in the case of the cargo collection work, for example, after the vehicle body 1 is brought close to the rack shelf 21 by the traveling motor 16, the fork 7 is raised together with the mast 8 by the lifting device 31. Next, the reach device 32 is driven to advance the fork 7 together with the mast 8 so that the fork 7 is inserted into the rack shelf 21. Subsequently, the fork 7 is tilted by the tilt driving means 14 and the load 6 is placed on the fork 7 inserted. An operation process such as ensuring that it is placed is executed.
[0036]
Next, the arithmetic processing unit 17a determines whether or not a lift lowering switch (not shown) is on (S3). After the load 6 is placed on the fork 7, when the operator operates the operation lever 20 for lowering the fork 7 to lower the fork 7, the lift lowering switch is turned on accordingly. Subsequently, the part 17a takes in the detection output of the lifting height detecting means 33 and determines whether or not the lifting height of the fork 7 is a predetermined value (for example, 1.5 m) or more (S4).
[0037]
If the lifting height of the fork 7 is less than the predetermined value, the arithmetic processing unit 17a determines that the operator can easily see whether or not the fork 7 has fully extended to the outside of the rack shelf 21, and causes the lifting device 31 to On the other hand, a lift lowering command signal for lowering the fork 7 is output (S7). In response, the lowering valve of the hydraulic cylinder 10 of the elevating device 31 is turned on (opened) (S8), and the fork 7 is lowered together with the mast 8.
[0038]
On the other hand, if the lifting height of the fork 7 is equal to or greater than the predetermined value in step 4, the arithmetic processing unit 17a determines that it is difficult for the operator to visually check whether the fork 7 has extended to the outside of the rack shelf 21. Next, the detection output of the tilt detection means 39 is taken in, and it is determined whether or not the fork 7 is tilted beyond a predetermined angle (S6). As described above, since the presence or absence of the operation of the tilt drive means 14 does not affect the detection of the fork tilt by the tilt detection means 39, the tilt detection means 39 is used when the fork 7 and the rack shelf 21 are engaged. Only that detection signal is output.
[0039]
When it is confirmed that the fork 7 is not tilted beyond a predetermined angle based on the detection output from the tilt detection means 39, the arithmetic processing unit 17a does not contact the rack shelf 21 or the like. And a lift lowering command signal for lowering the fork 7 is output to the lifting device 31 (S7). As a result, the lowering valve of the hydraulic cylinder 10 of the lifting device 31 is turned on (opened) (S8), and the fork 7 is lowered together with the mast 8.
[0040]
On the other hand, if it is determined in step 6 that the fork 7 is tilted by a predetermined angle or more, there is a high possibility that the fork 7 is in contact with the rack shelf 21 or the like. Is operated, for example, a lamp is blinked or a buzzer is sounded to notify that the state of the fork 7 is abnormal and the descent is in a dangerous state (S9).
[0041]
Subsequently, the arithmetic processing unit 17a determines whether or not the lowering prohibition release switch 46 is turned on (S10). If the lowering prohibition release switch 46 is turned on, the fork 7 is always allowed to descend according to the will of the operator, so that the process proceeds to step 7 where the fork 7 moves down together with the mast 8.
[0042]
On the other hand, when the lowering prohibition release switch 46 is off, when the state of the fork 7 is abnormal, it is instructed to execute the lowering prohibition process of the fork 7. The arithmetic processing unit 17a outputs a lift lowering command stop signal for stopping the lowering operation of the fork 7 to the lifting device 31 even when the lift lowering switch is turned on in the previous step 3 (S11). As a result, the lowering valve of the hydraulic cylinder 10 of the elevating device 31 is turned off (closed) (S12), and the lowering of the fork 7 is stopped. At this time, the arithmetic processing unit 17a simultaneously stops the output of the drive pulse to the traveling motor 16, and also applies the electromagnetic brake of the vehicle body stopping means 47 to stop the vehicle body 1 from moving forward and backward. Thereby, safety can be further improved.
[0043]
Next, it is determined whether or not the key switch is on (S13). If the key switch is off, the operation process is terminated. If the key switch is on, the operation is continued. And return to step 2.
[0044]
If the lift lowering switch is turned off in step 3, the fork 7 is not lowered, and the process proceeds to step 11 and subsequent steps.
The above description is a control operation when performing a loading operation with a reach-type forklift, but the control operation when performing a loading operation is basically the same.
[0045]
【The invention's effect】
In the cargo handling vehicle according to the present invention, when it is detected that the fork has tilted in contact with a foreign object such as a rack shelf, control for prohibiting the fork descending operation is executed. Therefore, when loading and unloading work from / to the rack shelf at the elevated position, the fork is lowered until it reaches the safe position where the fork has moved out of the rack shelf and a margin is secured. Operation is prohibited. As a result, the occurrence of load collapse can be reliably and effectively prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main part of a control system provided in a reach-type forklift according to the present embodiment.
FIG. 2 is a side view showing an arrangement state of tilt drive means and tilt detection means provided in the vicinity of the fork.
FIG. 3 is a flowchart showing a control operation of the reach-type forklift according to this embodiment.
FIG. 4 is a side view showing the overall structure of a reach-type forklift according to the present embodiment and a conventional embodiment.
[Explanation of symbols]
7 Fork 8 Mast 14 Tilt drive means (hydraulic cylinder)
17 Controller 17a Arithmetic processing part (Descent prohibition means)
31 Lifting device 32 Reach device 33 Lift detection means
39 Tilt detection means
45 Reporting means 46 Lowering prohibition release switch 47 Car body stopping means

Claims (5)

In a forklift provided with a fork for placing a load on the vehicle body and a lifting device for driving the fork up and down along the mast, the fork is supported on the vehicle body so as to be tiltable. In addition, a tilt detecting means for detecting the tilt of the fork is provided, and when the tilt detecting means detects that the fork is tilted more than a predetermined angle, the fork descending operation by the lifting device is prohibited. A cargo handling vehicle characterized in that a descent prohibiting means is provided . Tilt driving means for tilting the fork with respect to the vehicle body is provided, and when the tilt detecting means detects fork tilting that does not depend on the tilt driving means, the fork descending operation by the lifting device is prohibited. The cargo handling vehicle according to claim 1 , wherein: A lifting height detecting means for detecting a lifting height of the fork by the lifting device; and the lowering prohibiting means is configured so that the lifting height of the fork detected by the lifting height detection means is not less than a predetermined value set in advance. 3. The cargo handling vehicle according to claim 1 , wherein the fork is prevented from descending under certain conditions. 4. The vehicle body stop device according to claim 1, further comprising a vehicle body stop device for stopping the vehicle body from moving forward and backward when the tilt detection device detects that the fork is tilted more than a predetermined angle. The listed cargo handling vehicle. 5. A reporting means for reporting that the fork is tilted more than a predetermined angle by the tilt detection means to report that the fork is in a descending danger state . Cargo handling vehicle described in 1.

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