JP2004075280A - Forklift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forklift capable of preventing other forklift or workers in the surroundings from coming into contact with the fork and preventing a worker from stumbling even when an operator leaves the forklift while the fork rises above predetermined height. <P>SOLUTION: When forlift work ends and a key switch is turned off (YES at S1) or an auto power off function operates (YES at S2), a lift cylinder of a hydraulic drive means is operated by a control means to lower the fork forcedly until it lands on a floor surface (S7) if a reach in switch of a reach in the detection means is off (NO at S5) by satisfying forced lowering conditions that a release switch is on (YES at S3) and lift height of the fork is above predetermined lift height (YES at S4). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a forklift that is started by turning on a key switch and at least moves a fork up and down by driving a hydraulic drive unit in accordance with an operation of a hydraulic operation unit.
[0002]
[Prior art]
Generally, when the operator leaves the forklift when finishing the forklift operation or charging the battery of the forklift, the fork should land on the floor so that the fork does not touch or trip. Need to be kept. For this reason, when the operation is completed, the operator operates the lifting hydraulic operating lever to land the fork on the floor, and then turns off the key switch to stop the control means.
[0003]
Also, after finishing the work, operate the lifting hydraulic operating lever to land the fork on the floor, and then, if you forget to turn off the key switch and leave the forklift, stop operating the forklift for a certain period of time. If not, a forklift with an automatic power-off function for automatically stopping the control means has been proposed (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2000-327298 (page 2-3, FIG. 2)
[0005]
[Problems to be solved by the invention]
However, if the operator leaves the forklift and parks the fork without landing on the floor, the forklift will not notice the fork located higher than the floor, and when another forklift or worker passes in front of the forklift, Sometimes contacted the fork and tripped. Also, if the operator leaves the forklift without the fork landing on the floor with luggage placed on the fork, the load is constantly applied to the cargo handling equipment, which may shorten the life of the chain and members. there were.
[0006]
Therefore, the present invention prevents the other forklifts and workers around the fork from contacting or tripping with the fork even when the operator leaves the forklift with the fork raised above the predetermined height. It is an object of the present invention to provide a forklift that can prevent the forklift.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a forklift which is activated by turning on a key switch and at least moves a fork up and down by driving a hydraulic drive unit in accordance with an operation of a hydraulic operation unit. Lift height detecting means for detecting the height of the fork, and when the key switch is turned off, if the height detecting means detects that the fork is kept above a predetermined height from the ground, Control means for judging that the fork forced lowering condition is satisfied, controlling the hydraulic drive means to lower the fork to the ground, and then enabling the key switch to be turned off. I have.
[0008]
According to the invention described above, even if the operation of the forklift is completed and the operator forgets to land the fork on the floor, turns off the key switch, and leaves the vehicle body as it is, the hydraulic drive unit is controlled by the control unit. As a result, the fork is automatically forcibly lowered to the floor, so that other forklifts or workers around the fork can be prevented from contacting or tripping with the fork.
[0009]
According to a second aspect of the present invention, in the forklift according to the first aspect, the control unit has an automatic power-off function of turning off power to each unit when no operation is performed for a predetermined period of time. When executing the auto power-off function, it is also determined that the forcible lowering condition is satisfied when the fork height detecting means detects that the fork remains above a predetermined height from the ground. The automatic power-off function is executed after the fork is lowered to the ground by controlling a hydraulic drive unit.
[0010]
According to the invention described above, even if the operator leaves the forklift without landing the fork on the floor during the operation with the key switch kept on, even if the preset predetermined time elapses, the control means: After the hydraulic drive means is controlled and the fork is automatically landed, the power to each unit is turned off by executing the auto power-off function. It is possible to prevent the worker from touching the fork or tripping.
[0011]
According to a third aspect of the present invention, in the forklift according to the first or second aspect, the fork is controlled to be higher than a predetermined height from the ground when controlled by the control means and the forced lowering condition is satisfied. And an alarm means for issuing an alarm.
[0012]
According to the above invention, when the forcible lowering condition is satisfied, the alarming means is controlled by the control means and an alarm is issued, and it is notified that the fork is located at the predetermined height or higher. It is possible to know that the vehicle has not landed, and it is possible to prevent other forklifts and workers around the vehicle from contacting or tripping with the fork.
[0013]
According to a fourth aspect of the present invention, in the forklift according to the first or second aspect, the forklift is provided with an alarm unit which is controlled by the control unit and which operates while the fork is descending when the forcible lowering condition is satisfied, and issues an alarm. It is characterized by having.
[0014]
According to the above invention, the warning means is controlled by the control means and an alarm is issued during the descent of the fork due to the satisfaction of the forcible descent condition, so that it is possible to know that the fork is in the descent operation, and that other surroundings can be known. It is possible to prevent a forklift or an operator from coming into contact with a fork or luggage during the descending operation.
[0015]
According to a fifth aspect of the present invention, in the forklift according to the third aspect, the hydraulic drive unit also has a function of operating the fork to reach forward and backward, and includes a load detection unit that detects the presence or absence of a load on the fork. The control means controls the warning means so as to issue a warning when the fork is detected by the load detection means while the fork is in the reach-in state when the forced lowering condition is satisfied.
[0016]
According to the invention described above, in the case of a reach type forklift having a function of moving the fork back and forth, if the fork continues to descend while the fork is in a reach-in state, the end of the luggage is caught on the straddle arm, and the luggage is inclined. Since there is a risk of collapse of the load, when the fork is in the reach-in state when the forcible descent condition is satisfied and the presence of the baggage is detected by the baggage detection unit, the warning unit is controlled by the control unit and a warning is issued, The operator can easily know that if the fork is lowered as it is, the collapse of the load may occur, and the collapse of the load due to the forcible lowering of the fork can be prevented.
[0017]
According to a sixth aspect of the present invention, in the forklift according to any one of the first, second, fourth, and fifth aspects, a canceling operation for canceling the fork lowering control by the control means when the forcible lowering condition is satisfied. Means is provided.
[0018]
According to the invention described above, the forcible lowering control of the fork by the control means when the forcible lowering condition is satisfied can be released by operating the release operating means. And maintenance of the forklift can be easily performed.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment in which the present invention is applied to a reach type forklift will be described with reference to FIGS. 1 is a perspective view of the entire reach type forklift, FIG. 2 is an enlarged view of a cab, FIG. 3 is a block diagram of a control system, and FIG. 4 is a flowchart for explaining the operation.
[0020]
The reach type forklift according to the present embodiment is configured as shown in FIG. That is, the reach type forklift 1 includes the traveling drive unit 2, the hydraulic drive unit 4, and a battery (not shown) which is disposed inside the vehicle body 3 and serves as a power source of these two units 2, 4. I have.
[0021]
A traveling motor (not shown) constituting the traveling driving means 2 and a hydraulic motor (not shown) constituting the hydraulic driving means 4 are arranged inside the rear of the vehicle body 3. A control means 8 (see also FIG. 3) for controlling a traveling motor (not shown) and a hydraulic motor (not shown) is provided inside the front of the vehicle body 3.
[0022]
The traveling driving means 2 includes the traveling motor, one driving wheel 9, two driven wheels 12, and two caster wheels (not shown). The drive wheel 9 is also driven by the traveling motor, and also has a function as a steered wheel that is steered by a handle 10 provided on a left portion of the cab 16. The driven wheel 12 is rotatably disposed at a front end of a pair of left and right straddle arms 11 provided to project forward of the vehicle body 3. The caster wheel is rotatably disposed at the lower right rear of the vehicle body 3 so as to follow the traveling direction of the vehicle body 3.
[0023]
The hydraulic drive unit 4 includes a mast 13 erected between the straddle arms 11 and a lift bracket (not shown) that moves up and down along the mast 13. Is supported, and the fork 14 is tilted in the front-rear direction by a tilt cylinder (not shown). The lift bracket is moved up and down by expansion and contraction of a lift cylinder 15 attached to the mast 13. Further, the expansion and contraction of a reach cylinder (not shown) connecting the mast 13 and the vehicle body 3 causes the mast 13 and the fork 14 to move together in the front-rear direction.
[0024]
Then, the operator stands on the cab 16 at the rear part of the vehicle body 3 and operates the forklift 1 by operating the operating device 20 disposed at the front part of the cab 16 in the standing posture. Has become. The detailed arrangement of the operation device 20 is as shown in FIG.
[0025]
That is, as shown in FIG. 2, the operating device 20 includes an accelerator lever 21 for adjusting the running direction and the running speed, a lift lever 22 a for raising and lowering the fork 14 as a hydraulic operating means 31, and a tilt lever 22 b for tilting the fork 14. And a reach lever 22c for moving the fork 14 in the front-rear direction.
[0026]
In addition, a switch 23 of a lighting accessory such as a headlight and a release switch 24 as a release operation means for releasing the forcible lowering control of the fork 14 when the forcible lowering condition is satisfied by the control means 8 described later are arranged. Have been. A key switch 25 for turning on and off the power supply to the control unit 8 and other parts is provided at a front portion of the cab 16, and a left leg portion of the cab 16 is provided for braking operation of the vehicle body 3. (Not shown) are disposed.
[0027]
As will be described in detail later, for example, a lift detecting means 33 composed of a potentiometer is attached to a lower portion of the mast 13, and the lift of the fork 14 is detected by the lift detecting means 33. Here, the lift detecting means 33 may be a device other than a potentiometer, such as a limit switch or a magnet switch, which can detect whether the fork 14 has a certain lift.
[0028]
Next, the configuration of the control system will be described with reference to the block diagram of FIG. As shown in FIG. 3, when the key switch 25 is turned on to start the forklift 1, power is supplied to the control unit 8 by a battery, and a power supply line to the traveling drive unit 2 and the hydraulic drive unit 4. Is turned on, and the forklift 1 is ready for traveling and hydraulic operation.
[0029]
On the other hand, when none of the operation units including the hydraulic operation unit 31 is operated for a predetermined time (for example, 10 minutes) set in advance, the control unit 8 continues to operate each unit even when the key switch 25 is in the ON state. Has a so-called auto power-off function for stopping power supply to the power supply.
[0030]
Then, as shown in FIG. 3, a non-contact type magnet sensor 35 (see FIG. 1) attached to the mast 13 side and a magnet 36 (see FIG. 1) attached to the upper surface of the straddle arm 11 are formed. The reach-in detecting means 34 detects whether the mast 13 is in the reach-in state, and the output of the reach-in detecting means 34 is taken into the control means 8. At this time, the magnet sensor 35 is turned off when the mast 13 reaches in, and the magnet sensor 35 is turned on when the mast 13 reaches out.
[0031]
Here, as the reach-in detecting means 34, a contact-type sensor such as a limit switch may be used in addition to the non-contact type, and in other words, it is sufficient that the reach-in of the mast 13 can be detected.
[0032]
The load detecting means 37, which is a load detecting means comprising a pressure sensor connected between the lift cylinder 15 and the hydraulic pipe, detects the presence or absence of the load on the fork 14, and outputs the output of the load detecting means 37 to the control means. 8. The load detecting means 37 detects a change in the pressure of the lift hydraulic pipe, and outputs a detection signal to the control means 8 if there is a load on the fork 14. Here, in addition to such a pressure sensor, a contact-type or non-contact-type sensor such as a limit switch may be used as the load detecting means 37. In other words, the load detecting means 37 can detect the presence or absence of a load on the fork 14. I just want it.
[0033]
Further, an alarm means 40 comprising, for example, a buzzer is provided, and the alarm means 40 is controlled by the control means 8 so as to emit an alarm sound under predetermined conditions as described later.
[0034]
Then, the control unit 8 controls each unit and executes the following processing. When the operation of the forklift 1 is completed and the key switch 25 is turned off by the operator, the output of the height detecting means 33 is taken into the control means 8 while the power supply of the control means 8 is held by itself. It is determined whether or not the fork 14 is at or above a predetermined lift (for example, 10 cm above the floor). If the fork 14 is at or above a predetermined height when the key switch 25 is turned off, the control means 8 determines that a predetermined forced lowering condition is satisfied, and outputs a forcible lowering signal of the fork 14 to the hydraulic drive means 4. Then, the lift cylinder 15 is driven, and the lift detected by the lift detection means 33 becomes zero, and the fork 14 is forcibly lowered until it almost lands on the floor surface. Thereafter, when the automatic lowering of the fork 14 is completed, the operation of turning off the key switch 25 is validated, that is, the control means 8 itself, which has held the power supply self, is disconnected from the battery, and the operation of turning off the key switch 25 is validated. It has become.
[0035]
When the key switch 25 is turned off and the fork 14 is to be stopped at a height equal to or higher than a predetermined lift (10 cm from the floor), the release switch 24 may be turned off. The means 8 determines that the descending control is unnecessary, and the output of the forced descending signal to the hydraulic drive means 4 is stopped. At this time, in order to notify the surrounding workers that the fork 14 is located above the floor, the control means 8 outputs an alarm control signal to the alarm means 40 and emits an alarm sound.
[0036]
By the way, in a state where the fork 14 is determined to be equal to or higher than the predetermined lift (10 cm from the floor surface), the magnet sensor 35 of the reach-in detection means 34 is off, that is, the reach-in state, and the load detection means 37 indicates that there is a load. When the detection is detected, the output of the forced lowering signal to the hydraulic drive unit 4 is stopped by the control unit 8, the forcible lowering of the fork 14 is stopped, and the alarm signal is output to the alarm unit 40 by the control unit 8. A warning sound is issued, and it is notified that if the fork 14 is lowered in the reach-in state as it is, load collapse may occur.
[0037]
Next, a control procedure when the key switch 25 is turned off will be described with reference to the flowchart of FIG. Now, as shown in FIG. 4, it is determined whether or not the key switch 25 of the forklift 1 is off (S1). If the result of this determination is YES, the process proceeds to step S3, while if the result of the determination is NO, It is determined whether or not the automatic power-off function has completed measurement and is operating (S2). If the decision result in the step S2 is NO, it is determined that the forklift 1 is being operated, and the process returns to the step S1 to continue the operable state. If the decision result in the step S2 is YES, the process proceeds to the next step S3. Then, it is determined whether or not the release switch 24 is turned on (S3).
[0038]
If the decision result in the step S3 is NO, the operator can judge that the automatic lowering operation of the fork is unnecessary, and the control means 8 disconnects the power from the battery to the control means 8 itself and turns off the key switch 25. The operation is validated (S8), and the operation ends thereafter. On the other hand, if the decision result in the step S3 is YES, it is determined whether or not the lift of the fork 14 detected by the lift detecting means 33 is equal to or higher than a predetermined lift (S4), and the result of this determination is NO. If so, the process proceeds to step S8.
[0039]
If the determination in step S4 is YES, it is determined whether or not the fork 14 is in the reach-in state based on the output of the magnet sensor 35 of the reach-in detecting means 34 (S5). If the determination result is NO, step S7 is performed. If the result of the determination is YES, the load detecting means 37 determines whether or not there is a load on the fork 14 (S6). If the result of the determination is NO, the flow proceeds to step S7. The automatic lowering operation is performed (S7) until the floor 14 substantially lands on the floor (until the height detected by the height detecting means 33 becomes zero) (S7), and thereafter, the process proceeds to the above-described step S3.
[0040]
If the result of the determination in step S6 is YES, the luggage is placed on the fork 14, and the fork 14 is in the reach-in state. It can be determined that there is a danger that the cargo will collapse due to being hooked. Therefore, the process does not proceed to step S7, the forcible lowering of the fork 14 is stopped, and the warning means 40 is controlled by the control means 8 to emit a warning sound. (S9).
[0041]
Therefore, according to the above-described embodiment, when the operator forgets to land the fork 14 on the floor surface after the operation of the forklift 1 and turns off the key switch 25 and leaves the forklift 1, the forced Assuming that the descent condition is satisfied, the fork 14 is automatically lowered to the floor surface by controlling the hydraulic drive means 4 by the control means 8, so that other forklifts or workers around the fork 14 may come into contact with the fork 14 or stumble. Can be prevented beforehand.
[0042]
Further, when the fork 14 is in the reach-in state when the forcible lowering condition is satisfied, the warning means 40 is controlled by the control means 8 and an alarm sound is emitted. The operator can easily know that there is a possibility that the fork 14 may be broken down, and can take a quick countermeasure to prevent the collapse of the load due to the forced lowering of the fork 14.
[0043]
In the above-described embodiment, even during the forcible lowering operation of the fork 14 due to the establishment of the forcible lowering condition, the controller 8 may control the alarm unit 40 to emit an alarm sound.
[0044]
Further, in the above-described embodiment, when the forklift 1 has the automatic power-off function, the forcible lowering condition is satisfied even when the automatic power-off function operates, and the fork 14 is forcibly lowered by the hydraulic drive unit 4. Although the description has been given of the case in which the forklift 1 is not provided with the automatic power-off function, it is needless to say that the present invention can be applied to the case where the forklift 1 does not have the automatic power-off function. In this case, if the fork 14 is at or above a predetermined lift when the key switch 25 is turned off, the fork 14 may be forcibly lowered assuming that the forcible lowering condition is satisfied.
[0045]
Further, in the above-described embodiment, the case has been described in which the release switch 24 for releasing the fork 14 from forcibly descending is provided, but the release switch 24 is not necessarily provided.
[0046]
Further, in the above-described embodiment, a case has been described in which a buzzer that emits an alarm sound is used as the alarm unit 40. However, the alarm unit 40 uses a display that displays an alarm status, a lighting element such as a lamp, or the like. Needless to say, any method may be used as long as it alerts the operator and the surrounding workers.
[0047]
Further, in the above-described embodiment, the case where the reach-in detecting unit 34 for detecting whether the vehicle is in the reach-in state is described. However, when it is determined that the operation is not necessary, the reach-in detecting unit 34 is not necessarily provided. Absent.
[0048]
Further, in the above-described embodiment, the case where the present invention is applied to a reach type forklift has been described. However, it is needless to say that the present invention can be applied to a forklift other than the reach type, and in this case, the above description is also applied. The same effect as the embodiment can be obtained.
[0049]
Further, the present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.
[0050]
【The invention's effect】
As described above, according to the first aspect of the present invention, even if the operation of the forklift is completed, the operator forgets to land the fork on the floor, turns off the key switch, and leaves the vehicle body as it is. Since the hydraulic drive means is controlled by the control means and the fork is automatically lowered to the floor, it is possible to prevent other forklifts and workers around the fork from contacting or tripping with the fork. Will be possible.
[0051]
According to the second aspect of the present invention, even if the operator leaves the forklift without landing the fork on the floor during the operation with the key switch kept on, even if the operator leaves the forklift for a predetermined time, After the passage of time, the control unit controls the hydraulic drive unit to automatically land the fork, and then the power to each unit is turned off by executing the auto power off function. In addition, it is possible to prevent other forklifts and operators around the fork from contacting or tripping with the fork.
[0052]
Further, according to the third aspect of the present invention, when the forcible lowering condition is satisfied, the control means controls the alarm means to issue an alarm, thereby notifying that the fork is positioned at a predetermined height or higher. Therefore, it is possible to know that the fork has not landed on the floor, and it is possible to prevent other forklifts or workers around the fork from contacting or tripping with the fork.
[0053]
According to the fourth aspect of the present invention, during the descent of the fork due to the establishment of the forcible descent condition, the warning means is controlled by the control means and an alarm is issued. Therefore, it is possible to prevent other forklifts and workers in the vicinity from coming into contact with the fork or the load during the descending operation.
[0054]
According to the invention described in claim 5, in the reach type forklift having a function of moving the fork forward and backward, the fork is in the reach-in state when the forced lowering condition is satisfied, and the presence of the baggage is detected by the baggage detecting means. When the fork is moved down, the warning means is controlled by the control means and an alarm is issued, so that the operator can easily know that if the fork is lowered as it is, the collapse of the load may be caused. Load collapse can be prevented beforehand.
[0055]
According to the sixth aspect of the present invention, since the forcible lowering control of the fork by the control means when the forcible lowering condition is satisfied can be released by operating the releasing operation means, the fork is raised even if the key switch is turned off. The forklift can be stopped in the state, and maintenance and the like of the forklift can be easily performed.
[Brief description of the drawings]
FIG. 1 is a perspective view of an entire reach type forklift according to an embodiment of the present invention.
FIG. 2 is an enlarged view of a cab of the reach type forklift according to the embodiment of the present invention.
FIG. 3 is a block diagram of a control system according to an embodiment of the present invention.
FIG. 4 is a flowchart illustrating an operation according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Forklift 4 Hydraulic drive means 8 Control means 14 Fork 24 Release switch (release operation means)
25 Key switch 33 Lift detecting means 34 Reach-in detecting means 37 Load detecting means (package detecting means)

Claims (6)

In a forklift that is started by turning on a key switch and driven by a hydraulic drive unit according to an operation of a hydraulic operation unit to at least raise and lower the fork,
Lift detecting means for detecting the lift of the fork,
When the key switch is turned off, if the fork height detecting means detects that the fork is kept at a predetermined height or higher from the ground, it is determined that the fork forcible lowering condition is satisfied, Control means for controlling the hydraulic drive means to lower the fork to the ground and then turning off the key switch. The control means includes:
When no operation is performed for a predetermined period of time, an auto power-off function for turning off power to each unit is provided.When the auto power-off function is performed, the fork is lifted from the ground by the lift detecting means. When it is detected that the fork is still rising above a predetermined height, it is determined that the forcible lowering condition is satisfied, and the automatic power-off function is performed after controlling the hydraulic drive means to lower the fork to the ground. The forklift according to claim 1, wherein: An alarm unit controlled by the control unit, wherein an alarm unit for issuing an alarm that the fork is kept at a predetermined height or higher from the ground when the forced lowering condition is satisfied is provided. 3. The forklift according to 2. The forklift according to claim 1, further comprising an alarm unit that is controlled by the control unit and that operates while the fork is being lowered when the forcible lowering condition is satisfied, and issues an alarm. The hydraulic drive unit also has a function of causing the fork to reach forward and backward, and includes a baggage detection unit that detects the presence or absence of a baggage on the fork,
The control means,
4. The forklift according to claim 3, wherein the forklift is controlled to issue an alarm when the fork is in a reach-in state when the forcible lowering condition is satisfied and the presence of a baggage is detected by the baggage detecting unit. The forklift according to any one of claims 1, 2, 4, and 5, further comprising release operation means for releasing the lowering control of the fork when the forcible lowering condition is satisfied by the control means. .

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