JP3812886B2 - forklift - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a forklift having a function of automatically stopping a fork at a predetermined lifting height.
[0002]
[Prior art]
Conventionally, a forklift equipped with a lifting height limiting function that prevents a fork that is lifted and lowered by manual operation from exceeding a preset lifting height in order to improve the workability of cargo handling work and reduce operator fatigue There is.
[0003]
In this type of forklift, for example, a wire is connected to the fork, a feed amount of the wire is detected by a rotary encoder, and an output of the rotary encoder is added / subtracted by a counter. Then, when the counter value reaches a counter value corresponding to a preset lifting height, the fork is stopped. The wire feed amount is a feed amount from a predetermined reference point, and a counter value corresponding to the fork rise from the reference point is obtained by this feed amount, and the lift of the fork is obtained corresponding to the count value. Here, the lift of the fork means the height from the ground.
[0004]
The reference point is, for example, a micro switch attached to the lower part of the mast. When the fork passes through the micro switch, the counter is cleared and the count value becomes 0, and the fork rises. A count-up is started accordingly. In order to turn on this micro switch, after turning on the key switch to turn on / off the power of the forklift, it is necessary for the fork to pass through the micro switch even once. The function begins to work.
[0005]
[Problems to be solved by the invention]
By the way, in normal forklift work, when leaving the vehicle at the end of the work, the key switch is turned off while the fork is grounded. After passing through the switch, the lift limit function starts working.
[0006]
However, some operators may end work without grounding the fork, forget to ground the fork, or may not be able to ground the fork due to an obstacle in front of the parking position. The key switch may be turned off while the fork is stopped at a position higher than the micro switch. For this reason, even if the key switch is turned on at the start of work and the fork is raised, the fork does not pass through the microswitch, so that the elevation limit function remains unworked.
[0007]
And if the worker raises the fork by mistakenly thinking that the lift restriction function is working even though the lift restriction function is not working, the fork will rise above the lift height that he wants to stop For example, in the case where the vicinity of the ceiling height of the building is set to the restricted lifting height, there is a risk of breaking through the ceiling.
[0008]
In consideration of such circumstances, the present invention can automatically stop the fork safely at a level lower than a set limit after the key switch is turned on even when the fork is stopped at a lift level higher than the reference point when the key switch is turned off. An object of the present invention is to provide a forklift.
[0009]
The present invention also provides a forklift that can prompt the operator to lower the fork below the reference point even when the fork is stopped at a height higher than the reference point when the key switch is turned off. Objective.
[0010]
[Means for Solving the Problems]
Here, the forklift assumed in the present invention is a key switch for turning on / off the power of the vehicle, a lifting height setting means for setting a setting limit lifting height of the fork provided in the vehicle, and measuring the lifting height of the fork. A lifting height measuring means, a reference point setting means for setting a reference point for measuring the lifting height of the fork, and a setting limit in which the lifting height of the fork measured by the lifting height measuring means is set in advance by the lifting height setting means. And a lift control unit that stops the lift of the fork when the lift is reached.
[0011]
The present invention is based on such assumptions. When the key switch is turned off, stop lift storage means for storing the lift of the fork at that time as the stop lift The lift height measuring means starts the lift height measurement with the stop lift height read from the stop lift height storage means when the key switch is turned on as an initial value, and the lift control unit includes the lift height measuring means. The fork is stopped when the lift of the fork measured reaches the set limit lift.
[0012]
According to this, the lift measuring means reads the stop lift from the stop lift storage means when the key switch is turned on, and starts the lift measurement with the stop lift as an initial value. The lift of the fork is measured without passing the point, and when the measured value of the lift measuring means reaches the set lift, the lift control unit stops the fork. Even if it never passes through the reference point, the effect that the elevation limiting function works can be obtained.
[0013]
After the key switch is turned off, the lift of the fork is lowered due to natural descent, etc., but it is unknown how much it actually descends. Therefore, the height of the fork when the key switch is turned on cannot be accurately determined, but there is no doubt that it is less than or equal to the height of the fork when the key switch is turned off. If the fork is stopped at the set limit lift measured on the basis of, the actual stop position is always below the set limit lift.
[0014]
Further, the other forklift according to the present invention prompts the operator to lower the fork below the reference point when the fork is stopped at a lift higher than the reference point when the key switch is turned off. In order to achieve the object of providing a forklift cargo handling device that can be used, the following technical means are employed.
[0015]
That is, notification means for notifying that the reference point is not set, When the key switch is turned off, stop lift storage means for storing the lift of the fork at that time as the stop lift The lift control unit compares the stop lift of the fork stored in the stop lift storage means when the key switch is turned on with the lift of the reference point stored in advance, and the stop lift is A technical means for operating the notification means when the reference point is higher than the reference point is adopted.
[0016]
According to this, if the stop lifting height of the fork is higher than the reference point when the key switch is turned off, the reference point for lift control of the fork is set until the operator moves the fork to the reference point after the key switch is turned on. This is notified to the operator, and this notification can prompt the operator to lower the fork to the reference point once.
[0017]
Further, another forklift according to the present invention urges the operator to lower the fork below the reference point when the fork is stopped at a height higher than the reference point when the key switch is turned off. In order to achieve the object of providing a forklift loading / unloading device that can perform the following, the following technical means are employed.
[0018]
That is, notification means for notifying that the reference point is not set, When the key switch is turned off, stop lift storage means for storing the lift of the fork at that time as the stop lift The lift control unit compares the stop lift of the fork stored in the stop lift storage means when the key switch is turned on with the lift of the reference point stored in advance, and the stop lift is When the reference point is higher and a fork raising operation is performed, a technical unit is used in which the notification unit is operated until the reference point is set.
[0019]
According to this, when the operator is willing to raise the fork, the operator is informed that the reference point for lifting height control of the fork has not been set, and the fork is once more securely connected to the reference point. Can be urged to descend.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
A forklift cargo handling apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0021]
FIG. 1 is a functional block diagram of a lift control device in a forklift cargo handling device according to an embodiment of the present invention. This lift control device detects the position of a lift operation lever in order to raise and lower a fork manually. Operating position detecting means 4, a lift control unit 5 comprising, for example, a microprocessor unit (MPU), a proportional control valve drive circuit 6, a proportional control valve 7, a motor drive circuit 8, and a hydraulic motor 9 Prepare.
[0022]
The lift control device also includes a lifting height setting means 1 for setting the setting limit lifting height and a lifting height measurement means 2 for measuring the lifting height of the fork in order to stop the fork at a preset setting lifting height. And a reference point setting means 3 for setting a reference point for height measurement by the height measurement means 2. The reference point setting means 3 includes a micro switch attached below the mast, reads an on / off signal from the micro switch, and inputs it to the lift control unit 5. When the micro switch is turned on by raising the fork, the count value of the rotary encoder, which is one component of the lifting height measuring means 2, is cleared to zero and counted up as the fork rises. The count value is read into the lift height measuring means 2 and input to the lift control unit 5. The counter value corresponds to the lift height of the fork, and the lift height of the fork can be obtained by obtaining the counter value.
[0023]
In this embodiment, the lifting height refers to the height from the ground to the fork. The measurement of the lift height of the fork by the lift height measuring means 2 refers to obtaining the height from the ground to the fork. That is, the amount by which the wire is fed from the reference point is detected as a count value by the rotary encoder which is one component of the lifting height measuring means 2 to directly obtain how much the fork has become higher than the reference point. Then, by adding the height from the reference point of the fork to the well-known height from the ground to the reference point, it is possible to finally obtain the lift height of the fork, that is, the height from the ground to the fork. Is. The height of the reference point from the ground is stored in advance in the storage unit of the lifting height measuring means 2.
[0024]
In addition, once the reference point setting means 3 is set by passing the fork through the micro switch, the set state is maintained while the key switch of the vehicle is turned on, and the key switch of the vehicle is turned off. It is canceled when it is done. That is, after the key switch for turning on / off the vehicle is turned on, the fork is raised even once (directly the lift bracket is raised), and the reference point setting means 2 is set when the micro switch is turned on even once. is there.
[0025]
Next, the lift control device notifies the operator of this when the fork is lifted without a reference point for height measurement after the key switch for turning on / off the vehicle is turned on. And a notification driving circuit 10 for driving the same.
[0026]
In addition, this lift control device includes, for example, a backup memory 12 that stores a plurality of types of setting limit lifting heights, and a backup power source for saving the storage of the backup memory 12 during key switch-off or the like. . The backup memory 12 is a specific configuration of the stop height storage means described in the claims. Further, the height of the reference point is stored in the backup memory 12 in advance.
[0027]
2 to 5 are flowcharts of the control program of the lift control device. As shown in FIG. 2, this control program is started when the key switch of the forklift is turned on, and whether or not the lift height is set first. Is determined (S1), and it is determined whether the program proceeds to the standard control routine RS or the elevation limit routine RA. After confirming that the key switch is not turned off after exiting one of the routines (S32), the limit lift is set as required (S33, S34) or the lift limit function is canceled. (S35, S36), the process returns to the first stage of the control program. When it is detected that the key switch is OFF (S32), the lift of the fork when the key switch is OFF, that is, the stop lift is stopped. After writing in the backup memory 12 which is a high storage means (S37), the program ends.
[0028]
FIG. 3 is a flowchart of the standard control routine. This standard control routine RS is the same as a lift control program for a general forklift that does not have a lifting height limit. For example, it is determined that a lift-down operation is performed. (S2) by turning on the hydraulic motor 9 via the motor drive circuit 8 and opening the proportional control valve 7 to the lift-down side via the proportional control valve drive circuit 6 to shorten the lift cylinder. The fork is lifted down (S3).
[0029]
Thereafter, when a stop operation for returning the lift lever to the neutral position is performed (S4), the hydraulic motor 9 is stopped via the motor drive circuit 8, and the proportional control valve 7 is set to the neutral position via the proportional control valve drive circuit 6. The lift-down is stopped by returning the valve to the closed position (S5).
[0030]
If it is determined that the ascending operation has been performed (S6), the hydraulic motor 9 is turned on via the motor drive circuit 8 and the proportional control valve 7 is opened upward via the proportional control valve drive circuit 6. The fork is raised by allowing the valve to elongate and extending the lift cylinder (S7).
[0031]
Thereafter, when a stop operation for returning the lift lever to the neutral position is performed (S8), the hydraulic motor 9 is stopped via the motor drive circuit 8, and the proportional control valve 7 is set to the neutral position via the proportional control valve drive circuit 6. When the valve is returned to the closed position, the fork is stopped from rising (S9).
[0032]
When the lift is set using the lift setting means 1 after the key switch is turned on, the lift control unit 5 checks the lift setting (S1) and enters the lift restriction routine RA. .
[0033]
Here, the lifting height setting means 1 only needs to be able to perform an operation for setting a setting limit lifting height. For example, the lifting height setting means 1 includes a push button switch, a panel switch, or the like corresponding to each floor of a standardized load storage shelf. When a push button switch, panel switch, or the like corresponding to any one of the floors is pressed, the lift control unit 5 reads the set limit lift corresponding to the switch from the backup memory 12 to selectively set the set limit lift. Is done. In addition, for example, a numeric keypad may be provided in the lift height setting means 1, and the setting limit lift height may be set to a numerical value specifically input by operating the numeric keypad.
[0034]
In this embodiment, a set limit height or a numerical value representative of this (here, the number of floors of the load storage shelf) is displayed on a display 11a provided with a color liquid crystal display device provided in the cab.
[0035]
FIGS. 4 and 5 are flow charts of the lifting height restriction routine. When the lifting height restriction routine RA is entered as shown in FIG. 4, first, the count value and the set restriction lifting height of the backup memory 12 are stopped. It is determined whether or not data such as the count value has been read (S10), and if it has not been read, the stop lift is read from the backup memory 12 and the lift height measuring means 2 or lift control unit 5 is set to the count value of the counter (hereinafter simply referred to as “counter”) incorporated in the counter 5 (S11). On the other hand, in the clear memory built in the lift control unit 5, the count value of the set limit lifting height to be compared with the count value of the counter is set. Next, it is checked whether or not the fork is positioned at the reference point (S12). In most cases, since the fork is not positioned at the reference point when the lift is set, the process of checking the operation of the lift lever is checked. Migrate to
[0036]
The order of checking the operation of the lift lever is not particularly limited. Here, the presence or absence of the lift-down operation is checked first (S13), and the presence or absence of the lift operation is checked when the lift-down operation is not performed (S13). S14).
[0037]
For the operation of the lift lever, for example, the position of the lift lever is detected by the potentiometer 4a of the operation position detecting means 4, and the output of the potentiometer 4a is converted into a digital signal value by the A / D converter 4b and given to the lift control unit 5. The lift control unit 5 recognizes how much and in what direction the lift lever is operated based on the digital signal value.
[0038]
However, in the stage of checking the operation of the lift lever (S13, S14), the amount of operation of the lift lever is not a problem, and it is only necessary to check in which direction the lift lever is operated. Instead of the converter 4b, the lift lever is turned on when the lift lever is operated in the upward direction, and is turned off when the lift lever is positioned at the neutral position, and the lift lever is operated in the lift down direction. The operation position detecting means 4 may be constituted by a lift-down operation detection switch composed of, for example, a micro switch which is turned on and turned off when positioned at the neutral position.
[0039]
When there is a lift-down operation, there is no particular problem, so lift-down is performed (S15) and the count value of the lift height measurement counter is counted down, as in the lift-down control in the standard control routine RS. (S16). That is, when the fork has never passed the reference point, the count value of the counter is counted up based on the count value of the stop lifting height read from the backup memory 12, that is, the initial value. The lift height is measured. Thereafter, when a stop operation for returning the lift lever to the neutral position is detected (S17), the lift-down is stopped (S18).
[0040]
If there is an ascending operation, as shown in FIG. 5, it is checked whether or not the fork has passed the reference point even once, and a reference point for height measurement is set (S19), and the reference point has been set. In this case, as will be described later, the counter is reset when the reference point passes, so that the same lift restriction as in the prior art is performed.
[0041]
That is, in response to the operation amount of the raising operation, the proportional control valve 7 is moved to the ascending side to raise the fork (S20), and accordingly the count value of the counter is counted up (S21). The reference measurement lift, that is, the count value of the counter is compared with the count value set in the clear memory, and when it is confirmed that the count value of the counter exceeds the set limit lift (S22), the rise Is stopped (S23).
[0042]
When the fork has been lifted without passing through the reference point so far, it is determined that the reference point has not been set (S19), the notifying means 11 is immediately activated (S24), and the reference point has not been set. In other words, the operator is informed that the ascending operation has been performed without passing through the reference point so far.
[0043]
The notification method is not particularly limited, but a method that allows the operator to recognize the notification without any particular attention is preferable. For example, a notification method that can be felt by the operator's vision or a notification that can be felt by the operator's hearing. The method is adopted.
[0044]
Notification methods that can be perceived by the operator's vision include notification methods such as lighting, extinguishing, flashing, turning, switching of lighting colors, displaying or not displaying notification marks, displaying or not displaying notification texts, etc. However, in this embodiment, a method of blinking the display of the set limit height on the display 11a is employed.
[0045]
In addition, examples of notification methods that can be perceived by the operator's hearing include a method of sounding a buzzer, chime, horn, etc., a method of playing instrument sounds, music, voice, etc. by electronic synthesis. In this embodiment, a buzzer is used. 11b is used.
[0046]
After the notification is activated, if it is confirmed that the lift of the fork measured by the lift measuring means 2, that is, the measured lift is less than the set limit lift (S25), the fork is raised (S26), Counting up is performed in addition to the count value of the stop lifting height set in the counter of the lifting height measuring means 2 (S27). Then, the measured lift, that is, the count value of the counter is compared with the count value set in the clear memory, and when the count value of the counter exceeds the set limit lift, the fork lift is stopped (S28). .
[0047]
In other words, if the fork has never passed the reference point, the lift restriction function has not worked in the past, but in this embodiment, even if the fork has never passed the reference point, The lifting height is measured by the lifting height measuring means 2 on the premise that there is the above-mentioned stopped lifting height, and when this measured value is equal to or higher than the above-described set lifting height, a lifting limit function for stopping the fork is obtained.
[0048]
By the way, when the fork is positioned lower than the reference point when the key switch is turned on, the reference point is set when the fork is raised and the reference point setting means 3 is driven, and the fork is moved to the reference point when the key switch is turned on. If the position is higher, the reference point is set by lowering the fork and driving the reference point setting means. And if a reference point is set, as mentioned above, the same height restriction as before is performed.
[0049]
As described above, when the ascent is started before the reference point is set, the notification means 11 is activated (S24). As shown in FIG. 4, the notification operation is performed when the fork passes the reference point. It is continued until it is confirmed that it has been done (S10, S11, S12, S29, S30). When the fork passes the reference point, the above-described lift measurement counter is reset and its number is set to 0 (S31), and thereafter the same lift restriction is executed until the key switch is turned off. become.
[0050]
The setting limit lifting height is set by performing a lifting height setting operation such as pressing a switch of the lifting height setting means 1 before the key switch is turned off (S33, S34). If a setting canceling operation such as pressing the switch twice is performed, the setting limit lifting height can be cancelled (S35, S36).
[0051]
Further, in the above embodiment, when the key switch is turned on, if the reference point is not set and the fork starts to be lifted, the notification means 11 is activated, but this is not limiting, and when the key switch is turned on. If no reference point is set, the notification means 11 may be activated.
[0052]
Further, in this embodiment, the set limit lift set in the backup memory 12 is written at the limit lift setting (S34), and the last set limit lift stored after the key switch is turned off is stored next time. After the key switch is turned on, the setting is canceled or rewritten by a new limit lifting setting.
[0053]
As described above, in the forklift according to this embodiment, after the key switch is turned on, if the reference point for the height measurement is not set, the notifying means 11 is activated almost simultaneously with the start of the lifting operation, Notifies that the fork has been lifted without passing through the reference point, recognizes that the function to stop the fork does not work at the set limit lift, and lowers the fork once to set the reference point. Encourage you to.
[0054]
After the key switch is turned on, when the lift operation is started after setting the lift height, the lift height of the fork is measured based on the stop lift height of the fork at the time when the key switch is turned off immediately before. The fork is automatically stopped when it reaches the set lifting height, so that the fork does not rise higher than the set lifting height, and it is possible to prevent damage to the ceiling and beams of the building and damage to the load. .
[0055]
【The invention's effect】
As described above, according to the invention of claim 1, When the key switch is turned off, the lift of the fork at that time is stopped and the lift is stored. And when the key switch is turned on, the lift height is measured by the lift height measuring means with the stop lift height read from the stop lift height storing means as an initial value, and the lift is measured when the lift height measurement reaches a set limit lift height. By stopping the fork by the control unit, even if the fork is lifted without passing through the reference point, the fork is surely automatically stopped at a lift below the set limit lift, and the fork is above the set limit lift It is possible to eliminate the risk of damaging the ceiling, beams, etc. of the building.
[0056]
According to the invention of claim 2, the key is stored in the stop lifting height storage means when the key switch is turned on. Stop lift of fork when key switch is turned off Is compared with the pre-stored lift of the reference point, and if the stop lift is higher than the reference point, the lift control unit activates the notification means, thereby prompting the operator to set the reference point. In addition, it is possible to notify that the function of stopping the fork does not work at the set limit lifting height, and to call attention to the lifting height control.
[0057]
According to the invention of claim 3, the key is stored in the stop lifting height storage means when the key switch is turned on. Stop lift of fork when key switch is turned off And the lifted height of the reference point stored in advance, and if the stop lift is higher than the reference point and the fork is lifted, the lift control unit activates the notification means. By doing so, when the operator is willing to raise the fork, it is possible to prompt the setting of the reference point, and the function to stop the fork to the setting limit lift more reliably does not work Can be alerted and attention to lift control can be urged.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of the present invention.
FIG. 2 is a flowchart of a control program of the present invention.
FIG. 3 is a flow diagram of a standard control routine of the present invention.
FIG. 4 is a flowchart of a lifting height restriction routine of the present invention.
FIG. 5 is a flowchart of a lifting height restriction routine of the present invention.
FIG. 6 is a functional block diagram of a conventional example.
FIG. 7 is a flowchart of a conventional control program.
FIG. 8 is a flowchart of a conventional control program.
FIG. 9 is a flowchart of a conventional control program.
[Explanation of symbols]
1 Lifting height setting means
2 Lifting height measuring means
3 Reference point setting means
4 Operation position detection means
5 Lift control unit
11 Notification means
12 Backup memory

Claims (3)

A key switch for turning on / off the power of the vehicle, a lift setting means for setting a limit lift of a fork provided in the vehicle, a lift measurement means for measuring the lift of the fork, and a lift measurement of the fork A reference point setting means for setting the reference point of the fork, and when the lifting height of the fork measured by the lifting height measuring means reaches a set limit lifting height previously set by the lifting height setting means, the fork lift is stopped. In a forklift having a lift control unit,
When the key switch is turned off, it comprises stop lift storage means for storing the lift of the fork at that time as stop lift , and the lift measurement means reads from the stop lift storage means when the key switch is turned on. The lift control unit starts the lift measurement with the stop lift as an initial value, and the lift control unit stops the fork when the lift of the fork measured by the lift measuring means reaches the set limit lift. Forklift characterized by. A key switch for turning on / off the power of the vehicle, a lift setting means for setting a limit lift of a fork provided in the vehicle, a lift measurement means for measuring the lift of the fork, and a lift measurement of the fork A reference point setting means for setting the reference point of the fork, and when the lifting height of the fork measured by the lifting height measuring means reaches a set limit lifting height previously set by the lifting height setting means, the fork lift is stopped. In a forklift having a lift control unit,
An informing means for informing that the reference point is not set, and a stop lift storage means for storing the lift of the fork at that time as a stop lift when the key switch is turned off , are provided. When the control unit compares the stop lift of the fork stored in the stop lift storage unit with the key switch on and the lift of the reference point stored in advance, and the stop lift is higher than the reference point A forklift characterized in that the notifying means is operated. A key switch for turning on / off the power of the vehicle, a lift setting means for setting a limit lift of a fork provided in the vehicle, a lift measurement means for measuring the lift of the fork, and a lift measurement of the fork A reference point setting means for setting the reference point of the fork, and when the lifting height of the fork measured by the lifting height measuring means reaches a set limit lifting height previously set by the lifting height setting means, the fork lift is stopped. In a forklift having a lift control unit,
An informing means for informing that the reference point is not set, and a stop lift storage means for storing the lift of the fork at that time as a stop lift when the key switch is turned off , are provided. When the control unit compares the stop lift of the fork stored in the stop lift storage unit with the key switch on and the lift of the reference point stored in advance, and the stop lift is higher than the reference point And when the raising operation of a fork is performed, the said notification means is operated until the said reference point is set, The forklift characterized by the above-mentioned.

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