JPH0761790A - Control device for forklift - Google Patents

Abstract

PURPOSE:To provide a control device for a forklift, by which a designated fork height and the backward tilting attitude of a mast can be realized automatically. CONSTITUTION:A magnet 12 is fixed to an inner mast 3 in a forklift, and a lead switch 11 powered on in a position confronting with the magnet 12 with elevating of the inner mast 13 and a fork 6 to a designated position of an outer mast 2. Another magnet 13 is fixed to the outer mast 2, and a lead switch 14 powered on in a position confronting with the magnet 13 with backward tilting of the outer mast 2 is fixed in a designated position of a vehicle body. The inner mast 3 is elevated automatically and the outer mast 2 is tilted backyard by the power-on of a control switch 18, and the magnets 12, 13 are controlled in such a manner as to stop in designated height position and a designated backward tilting position facing to the lead switches 11, 14, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift control device, and is particularly useful when used to set the fork position and the mast position to a predetermined running position.

[0002]

2. Description of the Related Art A forklift truck is an industrial vehicle for loading and unloading which has a mast for raising and lowering a loaded load in front of a vehicle body so that it can be moved from place to place.

FIG. 12 is a perspective view showing an example of a standard forklift. As shown in the figure, the lift cylinder 1 is fixed to a pair of left and right outer masts 2, and the pair of left and right inner masts 3 are moved up and down with the outer mast 2 as a guide as the piston rod 1a expands and contracts. At this time, the outer mast 2 is fixed to the vehicle body 4 in front of the vehicle body 4. As a result, as the inner mast 3 moves up and down, the elevating part including the bracket 5 suspended on the chain (not shown) and the fork 6 for directly carrying the load moves up and down.

The tilt cylinders 7 are fixed to the vehicle body 4, and the respective piston rods 7 are provided.
The tip of a is fixed to the pair of left and right outer masts 2. Thus, the outer mast 2 is configured to incline in the front-back direction of the vehicle body 4 by the expansion and contraction of the tilt cylinder 7. The front mast of the inner mast 3 and the outer mast 2, which is integrated with the elevating part, is in the unloading of the load to be loaded on the fork 6, and the rear mist of the same part is in the rear mast.
It is used when traveling with luggage loaded.

The traveling posture of the forklift according to the prior art, that is, the posture in which the outer mast 2 is tilted backward and at the same time the fork 6 is held at a predetermined height (for example, 20 cm) from the ground surface is realized by a manual operation of the driver. There is.

[0006]

As described above, in the prior art, since the running posture is realized by the manual operation, it takes time to realize a predetermined running posture and some skill is required. . In cargo handling work using a forklift, the operation for moving to the running posture is the most frequent operation, and automation of this operation is desired.

In view of the above-mentioned prior art, it is an object of the present invention to provide a forklift control device capable of automatically realizing a predetermined fork height and a rearwardly inclined posture of a mast.

[0008]

The structure of the present invention for achieving the above object is to drive a lift cylinder through a chain in which an elevating part including a fork which is a loading part of a load and a bracket suspends the bracket to drive the vehicle body. In a forklift control device configured to move up and down along a mast arranged in the front and to tilt in the front-rear direction of the vehicle body by driving the tilt cylinder, the elevating part is at a predetermined height position with respect to the mast. The height position detecting means for detecting that, the rearward tilt position detecting means for detecting that the mast is at a predetermined rearward tilt position, and the control switch being turned on,
The lift cylinder raises and lowers the elevating part until the elevating part is located at a predetermined height position with respect to the mast, and the mast is in a predetermined rearward tilt position. And a control unit for tilting the mast backward by the tilt cylinder until it is detected by the backward tilt position detecting means.

[0009]

According to the present invention having the above-described structure, when the control switch is turned on, the elevating part is raised or lowered to automatically stop at a predetermined height position, and the mast is tilted backward to automatically move at a predetermined backward tilt position. Stop. Thus, the predetermined traveling posture is automatically realized.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. Note that the same parts as those in FIG.

FIG. 1 is a block diagram showing a control system of a control device for a forklift according to this embodiment, and FIG. 2 is a hydraulic circuit diagram showing the hydraulic system thereof.

As shown in FIG. 1, the control system of the present control system comprises a reed switch 11 fixed to the outer mast 2,
The magnet 12 fixed to the inner mast 3, the magnet 13 fixed to the outer mast 2, the reed switch 14 fixed to the vehicle body 4 (see FIG. 12), and the joystick levers 15 and 1.
6, a hydraulic pressure sensor 17, a control switch 18, a controller 19 which is a control unit, and a battery 20, and the controller 19 further includes an A / D converter 21, a switch input interface 22, a clock generator 23, and a CPU 2.
4, RAM 25, ROM 26, solenoid valve drive circuit 27 and power supply circuit 28.

Of these, the magnet 12 moves up or down together with the fork 6 and the inner mast 3 and is located at a position facing the reed switch 11 at the reed switch 11 side.
To operate. In this way, the magnet 12 is reed switch 1
The position opposite to 1 is a predetermined height position in the running posture (a height position of, for example, 20 cm from the ground surface).

The magnet 13 moves along with the forward tilt or backward tilt of the outer mast 2 accompanying the driving of the tilt cylinder 7, and the reed switch 1 with the backward tilt of the outer mast 2.
The reed switch 14 is operated at a position opposite to 4. In this way, the position where the magnet 13 faces the reed switch 14 is the predetermined rearward tilt position in the running posture.

The joystick levers 15 and 16 are levers for manually raising and lowering the fork 6 and tilting the outer mast 2 back and forth. That is, when the joystick lever 15 is tilted to one side, the fork 6 rises at a speed corresponding to the tilt amount, and when tilted to the other, the fork 6 descends at a speed corresponding to the tilt amount. Similarly, the outer mast 2 tilts forward by tilting the joystick lever 16 to one side, and tilts rearward by tilting to the other side. In addition, raising and lowering and tilting of both joystick levers 15 and 16 are stopped by moving them to the neutral position.

The hydraulic pressure sensor 17 detects the pressure of the pressure oil supplied to the lift cylinder 1, and thereby detects the load of the lifting portion (see FIG. 2). The control switch 18 is a switch for starting control for automatically realizing a predetermined traveling posture by turning on the control switch 18.

A / D converter 21 of controller 19
Is the joystick levers 15 and 16 and the hydraulic sensor 1
When analog signals are input from 7, the digital signals are converted into digital signals and output to the CPU 24. The switch input interface 22 outputs ON / OFF signals of the reed switches 11 and 14 and the control switch 18 to the CPU 24.

The CPU 24 performs predetermined arithmetic processing (details will be described later) on the basis of each of the signals input via the A / D converter 21 and the switch input interface 22, and the solenoid valve drive circuit 27 according to the arithmetic result. The electromagnetic proportional control valves 29, 30 and the unload valve 31 are controlled via the.

That is, as shown in the hydraulic circuit of FIG.
When the spools of the electromagnetic proportional control valves 29, 30 and the unload valve 31 move to one side due to the control current output by the controller 19, the engine 32 of the forklift truck
The pressure oil discharged from the pump 33 driven by is supplied to the lift cylinder 1 and the tilt cylinder 7 via the electromagnetic proportional control valves 29 and 30, and as a result, the piston rods 1a and 7a are extended to raise the elevating part. At the same time, the outer mast 2 is tilted forward. In addition, the electromagnetic proportional control valve 2
When the spools 9 and 30 move to the other side, the piston rods 1a and 7a are contracted to lower the elevating part and tilt the outer mast 2 backward.

In FIG. 2, 34 is an oil tank, 35 is a main relief valve, and 36, 37 and 38 are check valves.

FIG. 3 shows the arithmetic processing contents of the CPU 24.
It is a flowchart. Initializer as shown in the figure
After calibrating (Step S₁See), Joystick Lever
Output signal from -15 is a signal to lower fork 6.
Or whether it is a signal in the raising direction (step S₂, S
₃reference). As a result, the signal for lowering the fork 6
If there is, then calculate the lift lower lever and calculate the lever
Obtain the force value and then perform the maximum descent speed limit calculation.
Find the limit value (step S_Four, S_Fivereference). Continued
After clearing the automatic flag and the one-time tilt flag,
Compare the lever output value with the limit value, and depending on the result,
Control signal corresponding to the lever output value or limit value.
Output to the solenoid valve drive circuit 27 (step S₆, S₇，
S₈, S ₉reference).

Here, the automatic flag automatically controls the position of the fork 6 to a position in a predetermined traveling posture (a position where the reed switch 11 is turned on by the magnet 12) (hereinafter, referred to as an automatic traveling posture). (1) Tilt once flag means that the rearward tilt position of the outer mast 2 is automatically set to a position in a predetermined traveling posture (a position where the reed switch 14 is turned on by the magnet 13). (Hereinafter, referred to as automatic tilt attitude control) control mode. The once-tilt flag is a flag that is set every time tilt control is performed.

The calculation of the lift lowering lever in step S ₄ means the lever opening corresponding to the output signal from the joystick lever 15 and the CPU 2 as shown in FIG. 4A.
Table data representing the relationship with the lever output value corresponding to the control signal output from No. 4 is stored in advance, and the lever output value is obtained from the output signal of the joystick lever 15 and this table data. Also step S
The maximum descent speed limit calculation of ₅ means that table data representing the relationship between the load of the ascending / descending part and the limit value with respect to the lever output value as shown in FIG. The limit value is obtained from table data. That is, here, the magnitude of the maximum descending speed is adjusted according to the load so that the descending speed becomes constant regardless of the load.

If the result of the determination (steps S ₂ and S ₃ ) is that the signal is in the direction of raising the fork 6, the lift raising lever is calculated to obtain the lever output value, and the automatic flag and the tilt once flag are obtained. After clearing
And it outputs a control signal corresponding to the lever output value to the electromagnetic valve drive circuit 27 (see step _{S 10, S 11, S 12} ). Note that the lift-up lever calculation in step S _10, is to compute the lever output value by a table data as shown in the above-mentioned lift down lever calculated similarly to (see step S ₄₎ FIG. 4 (c).

On the other hand, when the manual operation is not performed and there is no output signal from the joystick lever 15 (in the case of neutral), traveling control (described in detail later) and position determination of the fork 6 are performed (step S _13). , S ₁₄ ). Here, the position determination of the fork 6 is a process of determining whether the magnet 12 representing the position of the fork 6 is above or below the reed switch 11. This is because when the operation of the joystick lever 15 is in the lower mode, the magnet 12 is below the reed switch 11 when the magnet 12 turns on the reed switch 11, and in the opposite case, the magnet 12 is turned on.
Is above the reed switch 11.

After the processing of any one of steps S ₈ , S ₉ , S ₁₂ , and S ₁₄ is completed, tilt control (described in detail later) and position determination of the outer mast 2 are performed (step S ₁₅ ,
See S _16). Here, the position determination of the outer mast 2 means that the magnet 13 representing the position of the outer mast 2 is the reed switch 14
It is a process of determining whether it is in front of or behind. This is because when the operation of the joystick lever 16 is in the backward tilt mode, when the magnet 13 turns on the reed switch 14, the magnet 13 is behind the reed switch 14, and in the opposite case, the magnet 13 is reed switch 14. It is judged to be in front of.

Finally, a predetermined calculated value is set to the electromagnetic proportional control valve 2
9,30 output to cause the lifting and tilting operation (see step S _17).

FIG. 5 is a flow chart showing in detail the traveling control of step S ₁₃ in FIG. As shown in the drawing, first lift lowered automatic mode or whether, and determines whether the lift-up or automatic mode (see step S _21, S _22), if not either the reed switch 11 is O
Determines N or not (step S _23). Here, the lift lowering automatic mode means that the control switch 18 is turned on and the magnet 12 is above the reed switch 11 at this time. What is the lift-up automatic mode?
The control switch 18 is turned on, and at this time, the magnet 12
Is below the reed switch 11.

[0029] As a result of the determination in step S _23, when the reed switch 11 is ON, clears the tilt once flag is set the output end value (see step S _24). Determined in step S _23, (see step S ₂₅₎ the control switch 18 determines whether the ON when reed switch 11 is OFF, in the case of OFF performs the processing in step S _24.

As a result of the determination in step S ₂₅ , when the control switch 18 is ON, that is, when the automatic traveling posture control is performed, it is determined whether or not the fork 6 is above the predetermined height position. This can be determined by referring to the processing result of step S ₁₄ in FIG. 3.

Step S₂₆As a result of the judgment of
If it is determined, the load response is based on Fig. 6 (a) and (b).
After performing the same speed increase / decrease value calculation and increase / decelerate value calculation,
Set initial value, automatic raising flag and raising speed increasing flag
(Step S₂₇, S₂₈, S ₂₉reference).

[0032] As a result of the determination in step S _26, when it is determined that the above compares the hydraulics and relief pressure (see step S _30), the lift cylinder 1 if not a hydraulic <relief pressure (see FIG. 1 ) Means at the stroke end, the initial value, the automatic lowering flag and the lift upper end flag are set. On the other hand, when the hydraulic pressure is less than the relief pressure, it means that the stroke end is not reached. Therefore, based on FIGS. 7A, 7B, and 7C, the constant speed calculation according to the load, the reduction acceleration value calculation, Deceleration value calculation and initial value,
It sets a lower automatic flag and lowered acceleration flag (see step _{S 32, S 33, S 34} , S 35).

As described above, the increase / decrease value of increase is calculated by raising the fork 6 at a constant speed regardless of the load, while gradually increasing the increasing speed and gradually decreasing it to a predetermined height position. This is to stop without shock. Also, the calculation of the acceleration / deceleration value and constant speed value
This is because the fork 6 is lowered at a constant speed regardless of the load, while the lowering speed is gradually increased, gradually decreased after a constant speed lowering, and is stopped at a predetermined height position without a shock.

[0034] As a result of the determination in step S _21, S _22, if it is determined that the lift lowers automatic mode and lift up the automatic mode, that is, when the lowering automatic flag and raising auto flag is set, the lift lowers automatically control and perform the lift-up automatic control (see steps S _36, S _37).

FIG. 8 is a flow chart showing in detail the lift lowering automatic control of step S ₃₆ in FIG. As shown in the figure, when it is detected in step S ₄₁ that the lift upper end mode is set (see step S _{30 in} FIG. 5), that is, when it is detected that the piston rod 1 a of the lift cylinder 1 is at the stroke end, the constant value is determined. The high speed calculation and the deceleration deceleration value calculation are repeated until the timer> over value, and the output value obtained by adding a constant to the previous value is applied to the solenoid proportional control valve 29.
(See FIG. 1) and repeats until the output value> constant speed value (steps S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₄₆ ,
See S _47). If it becomes timer> over value, it sets the hold flag is cleared to lift the upper end flag (see step S _48). If the output value> the constant speed value, the constant speed value is set (see step _S49 ).

In step S ₄₁ , the lift upper end mode is not set, that is, the piston rod 1 of the lift cylinder 1
When it is detected that a is not the stroke end, it is determined whether or not the speed-up mode is set (whether or not the speed-up flag is set) (see step _S49 ). Supplies the output value obtained by adding the acceleration value to the previous value to the solenoid proportional control valve 29 (see FIG. 1) until the reed switch 11 is turned on or the output value> the constant speed value (step S). ₅₀ , S ₅₁ , S ₅₂ ). As a result of the determination in step S ₅₀ , when the ON state of the reed switch 11 is detected, the speed increasing flag is cleared (see step S ₅₃ ). In accordance with the determination result in step S _52, sets the hold flag is cleared speed increasing flag when it is detected the output value> is a constant speed value (see step S _54).

Step S₄₉As a result of the judgment,
If it is detected that there is no, it is in the holding mode.
(Whether or not the hold flag is set) is determined (step
S ₅₅Read), if it is in the holding mode,
This holding mode is maintained until the ON state of switch 11 is detected.
When the ON state of the reed switch 11 is detected
Clear the hold flag at the point (step S₅₆, S₅₇).

[0038] As a result of the determination in step S _55, and supplies the output value obtained by subtracting the deceleration value from the previous value if it is not the holding mode is detected in the solenoid proportional control valve 29 (see FIG. 1),
Output value <until the stop value, repeating this, sets the output stop value is cleared automatically flag when it becomes an output value <end value (see steps _{S 58, S 59, S 60} ). Thus, after the reed switch 11 is turned on, the lift lowering control is completed with the fork 6 (see FIG. 1) ensuring a predetermined height position.

FIG. 9 is a flow chart showing in detail the automatic lift raising control of step S ₃₇ in FIG. As shown in the figure, if it is detected that the speed increasing mode in step S _61, until the reed switch 11 is turned ON, the electromagnetic proportional control output value obtained by adding the speed increasing value to the previous value is supplied to the valve 29 (see FIG. 1), until the output value> full open value, repeating this (see steps _{S 62, S 63, S 64} ). If the ON state of the reed switch 11 is detected in step S ₆₂ to clear the speed increasing flag (see step S _65). When the output value> full open value is detected in step _S64 , the output value is set to the full open value and the holding flag is set (see step _S66 ).

Step S₆₁As a result of the judgment,
If it is not detected, the lift lowering automatic
The same control as the control is performed. That is, step S₅₅，
S₆₆, Step S₅₆, S₆₇, Step S₅₇, S₆₈, Ste
Up S₅₈, S₆₉, Step S ₅₉, S₇₀, Step S₆₀，
S₇₁Correspond to each. Thus the reed switch
After 11 is turned on, the fork 6 (see FIG. 1)
Lift lift control is completed with the predetermined height position secured.
It

FIG. 10 shows step S in FIG.₁₅The chill
3 is a flowchart showing the details of the control. Shown in the figure
Operate the joystick lever 16 (see Fig. 1)
If it is tilted forward or backward,
In the case of tilting, tilt and tilt based on FIGS. 11 (a) and (b).
The tilt is calculated according to the amount of forward tilt.
The calculated value is output to the solenoid proportional control valve 30 (see Fig. 1).
Supply (step S ₈₁, S₈₂, S₈₃, S₈₄, S₈₅, S
₈₆reference).

On the other hand, when the joystick lever 16 is in the neutral position, it is determined whether the tilt automatic mode is set, that is, whether the control switch 18 (see FIG. 1) is ON and the tilt automatic flag is set. judgment, if not tilt automatic mode has not been implemented tilt once control, i.e. lowering the lift shown in and FIG. 5 does not stand tilting one flag in step S _21, S _22, of raising auto mode The output stop value is set on condition that it is neither (see steps S ₈₈ , S ₈₉ , S ₉₀ and S ₉₁ ). When it is detected in step S ₈₈ that the tilt once control is performed, and in steps S ₈₉ and S
_{At 90} , it is detected that one of the lift lowering mode and the raising automatic mode is selected, and the output stop value is set even when the tilt forward tilt is not performed (steps S ₈₈ , S ₈₉ , S ₉₀ , S ₉₂ ,
See _S91 ). The determination of whether or not inclined front tilt step S ₉₂ utilizes the results of the position determination of the outer mast 2 shown in FIG. That is, in the case where the magnet 13 shown in FIG.
Is. By the way, if it is not "tilt forward", it is not necessary to tilt the outer mast 2 backward.

If the result of determination in step S ₉₂ is that "forward tilt" is detected, it is necessary to perform automatic tilt attitude control. The output value which is the initial value of is set (see step S ₉₃ ).

When the tilt automatic flag is set and it is detected in step _S87 that the tilt automatic mode is set, the reed switch 14 is turned on, that is, the outer mast 2 is at the predetermined rearward tilt position. Until step S
_The tilt rearward tilt output value set in ₉₃ is supplied to the electromagnetic proportional control valve 30 to tilt the outer mast 2 rearward, and when the reed switch 14 is turned on, the tilt automatic flag is cleared and the output value is stopped. stopping the tilting operation after the outer masts 2 (refer to step S _94, S _95). Thus, the tilt control is completed in a state where the outer mast 2 secures the predetermined rearward tilt position.

[0045]

As described above in detail with reference to the embodiments, according to the present invention, the fork is automatically moved to the predetermined height position when the control switch is turned on, and the mast is moved to the predetermined rearward tilt position. It is possible to automatically move to a desired running posture automatically.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a hydraulic system according to an embodiment of the present invention.

3 is a flowchart showing the contents of arithmetic processing of a CPU 24 in FIG.

FIG. 4 is a characteristic diagram used for the lift lowering lever calculation, the maximum lowering speed limit calculation and the lift raising lever calculation in FIG.

FIG. 5 is a flowchart showing in detail “travel control” in FIG.

FIG. 6 is a characteristic diagram used for the lift increase speed increase value calculation and the lift increase deceleration value calculation in FIG.

FIG. 7 is a characteristic diagram used for constant speed value calculation, lift lowering speed increasing value calculation, and lift lowering deceleration value calculation in FIG.

8 is a flowchart showing in detail "lift lowering automatic control" in FIG.

FIG. 9 is a flowchart showing in detail “lifting automatic control” in FIG.

10 is a flowchart showing in detail "tilt control" in FIG.

11 is a characteristic diagram used in the tilt back tilt lever calculation and the tilt front tilt lever calculation of FIG.

FIG. 12 is a perspective view showing an example of a standard forklift.

[Explanation of symbols]

 1 Lift Cylinder 2 Outer Mast 3 Inner Mast 4 Car Body 5 Bracket 6 Fork 7 Tilt Cylinder 11,14 Reed Switch 12,13 Magnet 15,16 Joystick Lever 17 Hydraulic Sensor 18 Control Switch 19 Controller 29,30 Electromagnetic Proportional Control Valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuruji Kitabayashi 3,000, Tana, Sagamihara-shi, Kanagawa M / E / I Sagami High-Tech Co., Ltd.

Claims (1)

[Claims] 1. An elevating part including a fork and a bracket, which is a loading part of luggage, moves up and down along a mast arranged in front of a vehicle body by driving a lift cylinder via a chain for suspending the bracket, and the mast is In a control device for a forklift that is configured to tilt in the front-rear direction of a vehicle body by driving a tilt cylinder, a height position detection unit that detects that the lifting unit is at a predetermined height position with respect to a mast, and a mast has a predetermined position. The rearward tilt position detecting means for detecting the rearward tilting position and the lift of the control switch are turned on until the height position detecting means detects that the elevating part is at a predetermined height position with respect to the mast. The cylinder raises and lowers the lifting portion, and the tilt cylinder is moved until the rearward tilt position detecting means detects that the mast is at a predetermined rearward tilt position. A control unit for a forklift, comprising: a control unit for tilting the mast backward by a da.