JP2001097694A - Automatic lifting control device for forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic lifting control device capable of providing excellent positioning accuracy without starting shock and stop shock in automatic tilting controlling starting a control when a fork is located at a position close to a target height and having excellent operability. SOLUTION: A controller sets a gradient value and an upper limit value according to the size of an initial deviation value and outputs a smaller value of a value calculated by an arithmetic curve set so as to output the upper limit value when a position deviation value is larger than a deceleration point deviation value and to output a value between the upper limit value and a prescribed lower limit value when the position deviation value is smaller than the deceleration point deviation value and a value increased gradually from the gradient value from time when a control is started as a speed command value of a power generation means and an opening command value of a flow rate control valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic lift control device for a forklift.

[0002]

2. Description of the Related Art A forklift 40 as an industrial vehicle shown in FIG. 8 is a four-wheeled vehicle that drives a pair of left and right front wheels 41, 41 and steers a pair of left and right rear wheels 42, 42. Rear wheel 4
The steering of the wheels 2 and 42 is controlled by a steering wheel 44. An inner rail 12 is provided between a pair of left and right outer rails 11 erected at the front of a body frame 45 of a forklift so as to be able to move up and down. A finger board 51 having a fork 13 attached to the inner rail 12 is provided. Is mounted so as to be able to move up and down via a chain (not shown). The outer rails 11 are connected to a vehicle body frame 45 via a pair of left and right tilt cylinders 50, 50.
Is operated, the tilt cylinder 50 is driven to expand and contract, and the outer rails 11 and 11 are tilted.
A piston rod of a lift cylinder 14 disposed on the back surface of the outer rails 11, 11 is connected to the upper end of the inner rail 12, and when an operator operates the lift lever 22, the lift cylinder 14 is driven to expand and contract to operate as a working machine. Is moved up and down.

[0003] In the forklift 40 described above, conventionally, automatic lifting control capable of automatically controlling the lift height of the fork 13 to a predetermined set value during cargo handling work, and automatically setting the attitude of the fork 13 horizontally. In many cases, simplification and simplification of operation are achieved by an automatic positioning technology of a working machine such as tilt horizontal control. Here, the case of automatic lifting control will be described with reference to FIG. 9 as an example of simplification and simplification of operation. The same components as those in FIG. 8 are described with the same reference numerals. The other end of the chain 19 attached to the upper end of the finger board 51 having one end attached to the fork 13 is attached to the upper part of the outer rails 11 via a pulley 15 provided on the upper part of the inner rail 12. ing. One end of a rod 17 of a lift cylinder 14 as a working machine actuator for raising and lowering the fork 13 is connected to an upper end of the inner rail 12 via a support 18 projecting from the inner rail 12. Hydraulic piping is provided between the bottom chamber of the lift cylinder 14 and a hydraulic pump 20 driven by an electric motor 21 as power generating means for operating the lift cylinder 14 via a manual valve 81 for controlling expansion and contraction of the lift cylinder 14. It has been done. The head chamber of the lift cylinder 14 communicates directly with the hydraulic tank 35 via a hydraulic pipe. The manual valve 81 is operated by the lift lever 22, and the amount of operation of the manual valve 81 controls the amount of oil to the lift cylinder 14.

A lift sensor 23 for detecting the lift of the fork 13 is attached to the upper end of the outer rail 11 as a detector. The lift sensor 23 uses, for example, a reel-type encoder that measures the distance by the length of a wire 36 forming a reel.
And the other end is wound into the encoder. A limit switch 38 that outputs a lever operation signal LS of an ON signal when the lift lever 22 is operated is attached near the center of rotation of the lift lever 22.

[0005] Target lift setting means 25 for setting a target lift Ht as a target position at the time of automatic lift control of the fork 13.
Is a plurality of height selection switches 25a in which a plurality of target lifts are set in advance corresponding to the respective switches.
And an automatic switch 25b operated when selecting the automatic height control mode. The automatic switch 25b is provided on a front panel (not shown) of the operator's seat. Note that the automatic switch 2
When the switch 5b is turned on, the automatic command signal Sa output from the automatic switch 25b is turned on.

The controller 26 that controls the manual valve 81 and the electric motor 21 to control the lift to the target lift Ht includes:
The height H from the height sensor 23 and the limit switch 38
, A target lift Ht from the selection switch 25a, and an automatic command signal Sa from the automatic switch 25b are input via an input circuit (not shown). Further, the controller 26 outputs a duty D as a speed command value for controlling the rotation speed of the electric motor 21 to the electric motor 21 as power generating means via a drive circuit (not shown).

At the time of automatic lift control, the target lift setting means 2
The operator selects and sets a target lift by using the height selection setting switch 25a of No. 5, and turns on the automatic switch 25b. When the lift lever 22 is operated in a direction approaching the target lift, oil is sent to the lift cylinder 14 from a manual valve 81 as a flow control valve for controlling the amount of oil for expansion and contraction drive of the lift cylinder 14, and the inner rail 12 is moved. Ascending and descending, the fork 13 approaches the target lift. At this time, the deviation value calculation unit 70 of the controller 26 calculates the deviation value E between the target lift Ht and the lift H, and calculates the duty D by the duty calculation unit 71 based on the calculated deviation value E. The calculated duty D is used as an output permission determination unit 72
Is output to the electric motor 21 via the. Output permission determination unit 7
2 indicates that when the lever operation signal LS is an ON signal and the automatic command signal Sa is an ON signal, the duty D is
Output to 1.

The duty calculating section 71 calculates a duty D according to a calculation curve based on a deviation value E described below. That is, when the deviation value E is large, the duty D takes a constant value of the duty upper limit value Dd. Deviation E
Is smaller than the predetermined deceleration point deviation value Ed, the duty D is calculated to be smaller as the deviation value E becomes smaller, and the rotation speed of the electric motor 21 is reduced. Deviation E
Is a predetermined deviation threshold value Es, the duty D takes a predetermined duty lower limit value Ds. The deviation value E is equal to the deviation threshold value Es
Becomes smaller than the duty D, the duty lower limit D
From s to zero, the rotation speed of the electric motor 21 is set to zero, oil supply to the lift cylinder 14 is stopped, and the fork 13 is automatically stopped. Note that an area where the duty D between the deviation value E is zero and the deviation threshold Es is zero forms a predetermined dead zone set for stabilizing the control system.

[0009]

However, the above-mentioned prior art has the following problems. If the deviation value E is larger than the deceleration point deviation value Ed at the start of the automatic lift control, the duty D changes from the zero value to the duty upper limit value Dd. Then, a large amount of oil is discharged from the hydraulic pump 20, and the opening area of the manual valve 38 to the lift cylinder 14 is greatly opened by the operator. As a result, the stopped fork 13 suddenly starts operating, and the start shock at the start of operation is large. Also, at the start of the automatic lift control, if the deviation value E is smaller than the deceleration point deviation value Ed, that is, even if the control is started from a short distance to the target lift Ht, the duty D is equal to the magnitude of the deviation value E from the zero value. , The stopped fork suddenly starts operating, and the starting shock is large. The fork 13 reaches the target lift Ht while the rotation speed of the electric motor 21 started to rotate at the start of the control, and the duty D becomes zero, but the rotation speed of the electric motor 21 is reduced due to inertia. Immediately after the value becomes zero, the hydraulic pump discharges pressure oil. At this time, the fork 13 moves to the target lift H
Since t has been exceeded, the operator attempts to close the opening area of the manual valve 38 rapidly. As a result, the flow of the pressure oil is suddenly stopped, and a stop shock may occur. In particular, when the control is started from a close distance, the fork 13 reaches the target lift Ht and the fork 13 stops before the shock at the start of the operation converges, so that the shock at the stop is further increased due to resonance or the like. There is a problem that a predetermined positioning accuracy cannot be obtained due to the displacement of the position of No. 13 and operability is not good.

The present invention has been made in view of the above-mentioned problems. In the automatic lift control which starts control when a fork is located at a position close to a target lift, a starting shock,
It is an object of the present invention to provide an automatic lifting control device which can obtain excellent positioning accuracy without a stop shock and has good operability.

[0011]

In order to achieve the above object, a first aspect of the present invention provides a target lift setting means for setting a target lift of a fork, and a lift for detecting the lift of a fork. A high sensor, a power generating means whose rotational speed is controlled by a speed command, a hydraulic pump driven by the power generating means, a lift cylinder for controlling the lift of a fork, and a hydraulic pump and a lift cylinder A flow control valve for controlling the amount of oil to the lift cylinder based on an opening command for setting the opening area, and a target lift of the fork set by the target lift setting means and a lift detected by a lift sensor. When the position deviation is larger than a predetermined deceleration point deviation value, a predetermined upper limit value is output. When the position deviation is smaller than the predetermined deceleration point deviation value, a value that gradually decreases from the upper limit value to a predetermined lower limit value according to the position deviation. A controller for calculating and outputting at least one of the speed command value of the power generation means and the opening command value of the flow control valve based on the calculation curve set to output the output signal, and performing a fork positioning control. In the high control device, the controller includes a command value gradually increasing from the start of control based on a temporal gradient value according to the magnitude of the initial deviation value at the start of control, and an upper limit value according to the magnitude of the initial deviation value. Is output as a speed command value of the power generation means, which is smaller than the command value calculated by the calculation curve having the following.

According to the first invention, a time gradient value of a speed command value for commanding the magnitude of power generated by the power generating means for driving the lift cylinder in accordance with the initial deviation value at the start of control is set. I have. That is, when the initial deviation value is small, the speed command value is gradually increased by a small temporal gradient value as compared with when the initial deviation value is large. Thus, when the initial deviation value is small, the speed command value gradually increases gradually with time, so that the fork does not vibrate greatly at the time of starting and there is no fork start shock at the start of the automatic lifting control. Further, the upper limit of the speed command value is set according to the initial deviation value at the start of the control. That is, when the initial deviation value is small, the upper limit value is set smaller than when the initial deviation value is large. As a result, the upper limit of the fork speed is limited, so that the speed is reduced more gently than in the case where the upper limit is not limited, and there is no stop shock. As a result, since there is no start shock and stop shock, it is possible to obtain an automatic lift control device for a fork having excellent positioning accuracy and operability.

According to a second aspect of the present invention, there is provided a target lift setting means for setting a target lift of a fork, a lift sensor for detecting a lift of the fork, a power generating means whose rotation speed is controlled by a speed command, A hydraulic pump driven by the generating means, a lift cylinder for controlling the lift of the fork, and a hydraulic pump and a lift cylinder are provided between the hydraulic pump and the lift cylinder, and the amount of oil to the lift cylinder is set based on an opening command for setting an opening area. A flow rate control valve to be controlled, and a predetermined upper limit value when a positional deviation between the target lift of the fork set by the target lift setting means and the lift detected by the lift sensor is larger than a predetermined deceleration point deviation value. And outputs a value that gradually decreases from an upper limit to a predetermined lower limit in accordance with the position deviation when the speed is smaller than the predetermined deceleration point deviation value. And a controller for calculating and outputting at least one of the command value and the opening command value of the flow control valve, and performing a fork positioning control. The smaller of the command value gradually increasing from the start of control based on the temporal gradient value corresponding to the value of the value and the command value calculated by the calculation curve having the upper limit value corresponding to the magnitude of the initial deviation value The value is output as the opening command value of the flow control valve.

According to the second invention, the temporal gradient value of the opening command value to the flow control valve for controlling the power to the lift cylinder is set according to the initial deviation value at the start of the control. That is, when the initial deviation value is small, the speed command value is gradually increased by a small temporal gradient value as compared with when the initial deviation value is large. Thus, when the initial deviation value is small, the opening degree command value gradually increases gradually with time, so that the fork does not greatly vibrate at the time of starting, and there is no fork start shock at the start of the automatic lifting control. Also, the upper limit of the opening command value is set according to the initial deviation value at the start of control. That is, when the initial deviation value is small, the upper limit value is set smaller than when the initial deviation value is large.
As a result, the upper limit of the fork speed is limited, so that the speed is reduced more gently than in the case where the upper limit is not limited, and there is no stop shock. As a result, since there is no start shock and stop shock, it is possible to obtain an automatic lift control device for a fork having excellent positioning accuracy and operability.

According to a third aspect of the present invention, there is provided a target lift setting means for setting a target lift of a fork, a lift sensor for detecting a lift of a fork, a power generating means for controlling a rotation speed by a speed command, A hydraulic pump driven by the generating means, a lift cylinder for controlling the lift of the fork, and a hydraulic pump and a lift cylinder are provided between the hydraulic pump and the lift cylinder, and the amount of oil to the lift cylinder is set based on an opening degree command for setting an opening area. A flow rate control valve to be controlled, and a predetermined upper limit value when a positional deviation between the target lift of the fork set by the target lift setting means and the lift detected by the lift sensor is larger than a predetermined deceleration point deviation value. And outputs a value that gradually decreases from an upper limit to a predetermined lower limit in accordance with the position deviation when the speed is smaller than the predetermined deceleration point deviation value. And a controller for calculating and outputting at least one of the command value and the opening command value of the flow control valve, and performing a fork positioning control. The smaller of the command value gradually increasing from the start of control based on the temporal gradient value corresponding to the value of the value and the command value calculated by the calculation curve having the upper limit value corresponding to the magnitude of the initial deviation value The values are output as a speed command value of the power generation means and an opening command value of the flow control valve.

According to the third invention, the temporal gradient value of the speed command value and the opening command value is set according to the initial deviation value at the start of control. That is, when the initial deviation value is small,
The speed command value is gradually increased by a temporal gradient value smaller than when the initial deviation value is large. Thus, when the initial deviation value is small, the speed command value and the opening command value gradually increase gradually with time, so that the fork does not greatly vibrate at the time of starting and there is no fork start shock at the start of the automatic lifting control. . Further, the upper limit of the speed command value and the opening command value is set according to the initial deviation value at the start of the control. That is, when the initial deviation value is small, the upper limit value is set smaller than when the initial deviation value is large. As a result, the upper limit of the fork speed is limited, so that the speed is reduced more gently than in the case where the upper limit is not limited, and there is no stop shock. As a result, since there is no start shock and stop shock, it is possible to obtain an automatic lift control device for a fork having excellent positioning accuracy and operability.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a hardware configuration. The same components as those in FIGS. 8 and 9 will be described with the same reference numerals. Here, the description of the same configuration as that described with reference to FIGS. 8 and 9 is omitted, and only a different configuration will be described. FIG.
1 is that the control valve is changed from the manual valve 81 to the electromagnetic proportional valve 16, and the lift lever that operates the control valve is changed to the lift lever 22 that is not mechanically connected to the control valve. are doing. In FIG. 1, a lever operation amount detector 24 that detects a lever operation amount Lev is provided near the center of rotation of the lift lever 22 as a detector. In addition, the limit switch 38 is deleted with the change of the form of the lift lever 22. The input / output signals of the controller 26 shown in FIG.
And the automatic command signal Sa is transmitted to the controller 26 as in FIG.
However, the lever operation signal LS is deleted from FIG. The controller 26 outputs the motor duty command value Dm and the electromagnetic proportional valve command value Sv to the electromagnetic proportional valve 16.

Next, the configuration of the controller 26 will be described with reference to FIG. In FIG. 2, it is assumed that the element of the source of the arrow having the dotted line acts on the operation of the target element. The controller 26 has eight operation units, three determination units, two generators, and one storage unit described below. First, as a calculation unit, a deviation value calculation unit 70, a duty calculation unit 71, an opening command value calculation unit 73, a lever command value calculation unit 74, a duty time gradient value calculation unit 83, an opening command value time gradient value calculation unit 84, A duty upper limit calculator 85 and an opening command upper limit calculator 86 are provided. Next, an output permission determination unit 72, an opening command value minimum value determination unit 79, and a duty minimum value determination unit 89 are provided as determination units. The generator includes a start duty generator 87 and a start opening command value generator 88. One storage unit is the start deviation value storage unit 82.

An automatic command signal Sa and a lever operation amount Lev are acting on a start deviation value storage unit 82, and a deviation value E when the automatic command signal Sa and the lever operation amount Lev become an ON signal is stored as an initial deviation value. It is stored in the start deviation value storage unit 82 as Ez. The deviation value calculation unit 70
A deviation value E between the target lift Ht and the lift H is calculated and output to the duty calculator 71 and the opening command value calculator 73. The duty calculator 71 calculates the duty D by using a calculation curve based on the deviation value E in the same manner as described with reference to FIG.
Is calculated and output to the minimum duty value determination unit 89.
The opening command value calculation unit 73 calculates the opening command value V using a calculation curve based on the deviation value E described below. That is, the opening command value V when the deviation value E is large takes a constant value of the opening command value upper limit value Vd. In a region where the deviation value E is smaller than a predetermined deceleration point deviation value Ed, the opening command value V is calculated to be smaller as the deviation value E becomes smaller, and the opening area of the electromagnetic proportional valve 16 is made smaller. The opening command value V when the deviation value E is a predetermined deviation threshold value Es takes a predetermined opening command value lower limit value Vs. When the deviation value E becomes smaller than the deviation threshold value Es, the opening degree command value V changes from the opening degree command value lower limit value Vs to zero value, the opening area of the electromagnetic proportional valve 16 becomes zero value, and the oil supply to the lift cylinder 14 is performed. And the fork 13 is automatically stopped. Further, the calculated opening command value V is output to the opening command value minimum value determination unit 79. The lever command value calculation unit 74 calculates a lever command value VLev for controlling the electromagnetic proportional valve 16 based on the lever operation amount Lev, and outputs the calculated VLev to the opening command value minimum determination unit 79. The lever command value calculation unit 74 is provided with the electric motor 2.
1 is calculated, and the calculated motor command value DLev is output to the minimum duty value determination unit 89.

A duty time gradient value calculator 83 calculates a duty time gradient Kd according to the initial deviation value Ez at the start of control stored in the start deviation value storage unit 82, and calculates the calculated duty time gradient Kd as a start duty. It is output to the generation unit 87. The duty time gradient Kd in the duty time gradient value calculating unit 83 is obtained by calculating the point (first gradient deviation value E1 and first duty gradient value Kd1) by taking the initial deviation value Ez on the horizontal axis and the duty time gradient Kd on the vertical axis. Point (gradient second deviation value E2, duty second
It is calculated by an equation represented by a straight line passing through the gradient value Kd2). At this time, the first gradient value E1 is smaller than the second gradient value E2, and the first duty gradient value Kd1 is smaller than the second duty gradient value Kd2. The opening command value time gradient value calculation unit 84 calculates the opening command value time gradient Kv according to the initial deviation value Ez, and outputs the calculated opening command value time gradient Kv to the start opening command value generation unit 88. are doing. The opening command value time gradient Kv in the opening command value time gradient value calculation unit 84 is obtained by calculating the point (gradient first deviation value E1) by taking the initial deviation value Ez on the horizontal axis and the opening command value time gradient Kv on the vertical axis. , An opening command value first gradient value Kv1) and a point (the second gradient value E2, the opening command value second gradient value Kv2). At this time, the opening command value first gradient value Kv1 is smaller than the opening command value second gradient value Kv2.

The duty upper limit calculator 85 calculates the duty upper limit Dd according to the initial deviation value Ez, and acts on the duty calculator 71 to calculate the duty upper limit Dd as the upper limit of the calculation curve of the duty calculator 71. Set as The duty upper limit value Dd in the duty upper limit value calculation unit 85 can be calculated as a point (the upper limit first deviation value e) by taking the initial deviation value Ez on the horizontal axis and the duty upper limit value Dd on the vertical axis.
1, duty first upper limit value Dd1) and point (upper limit second value)
It is calculated by a mathematical expression represented by a straight line passing through the deviation value e2 and the second upper limit value Dd2 of the duty. At this time, the upper limit first deviation value e1 is smaller than the upper limit second deviation value e2, and the duty first upper limit value Dd1 is the duty second upper limit value Dd.
It shall be smaller than 2. Opening command value upper limit calculation unit 8
6 calculates the opening command value upper limit value Vd in accordance with the initial deviation value Ez, works on the opening command value calculating unit 73, and calculates the opening command value upper value Vd calculated by the opening command value calculating unit 73. Set as the upper limit of the curve. Opening command value upper limit calculation unit 8
In FIG. 6, the opening command value upper limit value Vd is obtained by taking the initial deviation value Ez on the horizontal axis and the opening command upper limit value Vd on the vertical axis (the upper limit first deviation value e1, the opening command value first upper limit). Value Vd1) and point (upper limit second deviation e2, opening command value second upper limit Vd)
It is calculated by an equation shown by a straight line passing through 2). At this time, the opening command value first upper limit value Vd1 is smaller than the opening command value second upper limit value Vd2.

The start duty generating section 87 calculates the time t
Is zero, that is, when the automatic lifting control is started, a start duty Dt that gradually increases with the input duty time gradient value Kd from the duty lower limit value Ds is generated, and the generated start duty Dt is reduced to the minimum duty. The value is output to the value determination unit 89. When the time t is zero, that is, when the automatic lift control is started, the start opening command value generation unit 88 temporally calculates the opening command value time gradient value Kv input from the opening command value lower limit value Vs. And the generated start opening command value Vt is generated.
Is output to the opening command value minimum value determination unit 79.

The opening command value minimum value judging section 79 selects the minimum value among the start command value Vt, the opening command value V and the lever command value VLev as the electromagnetic proportional valve command value Sv, and selects the output permission judging section 72. Output to Further, the minimum duty value determination unit 89 includes a start duty Dt, a motor command value D
The minimum value among Lev and the duty D is selected as the motor duty command value Dm, and is output to the output permission determination unit 72. The automatic command signal Sa and the lever operation amount Lev are acting on the output permission determination unit 72, and the automatic command signal Sa
When the lever operation amount Lev is an ON signal, the motor duty command value Dm and the electromagnetic proportional valve command value Sv are output to the electric motor 21 and the electromagnetic proportional valve 16, respectively.

Here, the operation of the present embodiment will be described. When the automatic switch 25b of the target lift setting means 25 is turned on and a switch of the height selection switch 25a corresponding to the target lift Ht is selected and turned on, the automatic command signal Sa
Is output to the start deviation value storage unit 82. Then, the operator operates the lift lever 22 to operate the lever operation amount L.
When ev occurs, the initial deviation value Ez is stored in the start deviation value storage unit 82. The duty upper limit value calculation unit 85 calculates the duty upper limit value Dd according to the initial deviation value Ez, and the duty upper limit value calculation unit 85 operates the duty calculation unit 71 to calculate the duty upper limit value Dd.
d is set as the upper limit value of the calculation curve of the duty calculation unit 71. When the initial deviation value Ez is equal to or more than the upper limit second deviation value e2, the duty upper limit value Dd takes the duty second upper limit value Dd2, and the initial deviation value Ez is larger than the upper limit first deviation value e1 and the upper limit second deviation e1. When the value is smaller than the value e2, the duty upper limit value Dd assumes Ddx. Based on the duty upper limit value Dd determined in this way, a calculation curve relating to the deviation value E of the duty D shown in FIG. Similarly, the opening command value upper limit value calculation unit 86 calculates the opening command value upper limit value Vd according to the initial deviation value Ez. Is set as the upper limit of the calculation curve of the opening command value calculation unit 73. When the initial deviation value Ez is greater than or equal to the upper limit second deviation value e2, the opening command value upper limit V
d is the opening command value second upper limit value Vd2, and the initial deviation value E
When z is larger than the upper limit first deviation e1 and smaller than the upper limit second deviation e2, the opening command value upper limit Vd becomes V
dx. The deviation value E of the opening command value V shown in FIG.
A calculation curve for the opening degree command value calculation section 73 is set.

Further, the duty time gradient value K is calculated by the duty time gradient value calculator 83 in accordance with the initial deviation value Ez.
d is calculated and output to start duty generating section 87. When the initial deviation value Ez is equal to or greater than the gradient second deviation value E2, the duty gradient value Kd becomes the duty second gradient value K
When d2 is taken and the initial deviation value Ez is larger than the first gradient deviation value E1 and smaller than the second gradient deviation value E2, the duty time gradient value Kd takes Kdx. With the duty time gradient value Kv set in this way, the start duty Dt calculated to gradually increase with time from the duty lower limit value Ds is the minimum duty value determination unit 89.
Is output to Looking at the relationship between the duty D and the deviation value E, when the automatic lift control is started when the initial deviation value Ez is large, the duty D becomes the duty lower limit of the point P1 as shown by a white arrow in FIG. From the value Ds, the temporal gradient value increases toward the second duty upper limit value Dd2 by the second duty gradient value Kd2. Initial deviation value E
When z is small, the temporal gradient value of the duty D gradually increases from Kdx at the duty lower limit value Ds at the point P2, as indicated by the black arrow in FIG.

Further, an opening command value time gradient value calculating section 84 calculates an opening command value time gradient value Kv according to the initial deviation value Ez, and outputs the calculated value to a start opening command value generating section 88. When the initial deviation value Ez is equal to or greater than the gradient second deviation value E2, the opening command value gradient value Kv takes the opening command value second gradient value Kv2, and the initial deviation value Ez is larger than the gradient first deviation value E1. When the difference value is smaller than the second deviation value E2, the opening command value time gradient value Kv assumes Kvx. The start opening command value Vt calculated to gradually increase from the opening command value lower limit value Vs with time based on the thus set opening command value time gradient value Kv is the opening command value minimum value determination unit. It is output to 79. When the automatic lift control is started when the initial deviation value Ez is large, the opening command value V is temporally shifted from the opening command value lower limit value Vs at the point Q1 as shown by a white arrow in FIG. The gradient value is the opening command value second gradient value Kv
2, the opening degree command value increases toward the second upper limit value Vd2. When the initial deviation value Ez is small, the temporal gradient value of the opening command value V gradually increases from the opening command value lower limit value Vs at the point Q2 by Kvx as indicated by a black arrow in FIG.

On the other hand, the minimum value of the start duty Dt, the motor command value DLev, and the minimum value of the duty D output from the duty calculation unit 71 are prepared in the minimum duty value determination unit 89 as the motor duty command value Dm output to the electric motor 21. You. Further, the minimum value of the lever command value VLev, the start command value Vt, and the opening command value V output from the opening command value calculating unit 73 is prepared in the opening command value minimum determining unit 79 as the electromagnetic proportional valve command value Sv. You. Next, when the operator operates the lift lever 22 in a direction in which the fork 13 approaches the target lift Ht, since the automatic command signal Sa is already an ON signal, the duty minimum value determination unit 8
9 and the electromagnetic proportional valve command value Sv prepared in the opening command value minimum determination unit 79.
Are permitted to be output by the output permission determination unit 72 and output to the electric motor 21 and the electromagnetic proportional valve 16 respectively. Then, the electric motor 21 starts rotating, pressure oil from the hydraulic pump 20 is supplied to the lift cylinder 14 via the electromagnetic proportional valve 16, and the fork 13 approaches the target lift Ht. At this time, when the lift lever 22 is not operated or the automatic command signal Sa is an off signal, the output permission determination unit 7
2, the output is not permitted, so that the duty D to the electric motor 21 and the solenoid proportional valve command value Sv to the solenoid proportional valve 16 maintain zero values, and the lift cylinder 14 does not expand or contract.

Next, the temporal change of the deviation value E, the duty D and the opening command value V by the above configuration will be described with reference to FIG. The two-dot chain line in FIG. 5 shows a temporal change of the deviation value E, the duty D and the opening command value V when the automatic height control has a large deviation value E at the start. Further, the dotted line shows a temporal change of each of the state quantities when there is a small deviation value E at the start of the control. When the time t in the case of having the large deviation value E is zero, the duty D
Has a duty lower limit value Ds, and the opening command value V has an opening command value lower limit Vs. As the time t elapses, the duty D gradually increases toward the second duty upper limit value Dd2 by the temporal gradient value of the second duty gradient value Kd2, and after reaching the second duty upper limit value Dd2, the deviation D The second duty upper limit Dd2 is held until the value E reaches the deceleration point deviation Ed. When the deviation value E becomes smaller than the deceleration point deviation value Ed, the deviation value E becomes a deviation threshold value Es while taking a value on a straight line that gradually decreases from the second duty upper limit value Dd2 shown by a two-dot chain line in FIG. To become smaller. If the duty D calculated in accordance with the deviation value E becomes smaller before the duty D gradually increasing with the temporal gradient reaches the second duty upper limit value Dd2, the duty D is calculated in accordance with the deviation value E. The smaller duty D is output to the electric motor 21. When the deviation value E reaches the deviation threshold value Es, the duty D becomes zero, and the rotation of the electric motor 21 stops. The opening command value V gradually increases toward the opening command value second upper limit value Vd2 by the temporal gradient value of the opening command value second gradient value Kv2 as the time t elapses similarly to the duty D. After reaching the opening command value second upper limit value Vd2, the opening command value second upper limit value Vd2 is held until the deviation value E reaches the deceleration point deviation value Ed. When the deviation value E becomes smaller than the deceleration point deviation value Ed, the deviation takes a value on a straight line that gradually decreases from the opening command value second upper limit value Vd2 indicated by the two-dot chain line in FIG. 4 to the opening command value lower limit value Vs. The value E decreases to the deviation threshold value Es. If the opening command value V calculated according to the deviation value E becomes smaller before the opening command value V gradually increasing with the temporal gradient reaches the opening command value second upper limit value Vd2, it becomes smaller. , The smaller opening degree command value V calculated according to the deviation value E is output to the electromagnetic proportional valve 16. When the deviation value E reaches the deviation threshold value Es, the opening command value V becomes zero, and the opening area of the electromagnetic proportional valve 16 is closed.

The dotted line in FIG. 5 shows the temporal change of the deviation value E, the duty D and the opening command value V when there is a small deviation value E at the start of the automatic lift control. The temporal change of the duty D when the deviation value E at the start of control is small is equivalent to the change pattern of the duty D when the deviation value E is large, but gradually increases from the duty lower limit value Ds when the time t is zero. This is a pattern in which the temporal gradient value is changed from the second duty gradient value Kd2 to Kdx, and the upper limit value is changed from the second duty upper limit value Dd2 to Ddx. Also, the opening command value V when the deviation value E at the start of control is small.
Is equivalent to the change pattern of the opening command value V when the deviation value is large, but the temporal gradient value gradually increasing from the opening command value lower limit value Vs when the time t is zero is increased. This is a pattern in which the degree command value second gradient value Kv2 is changed to Kvx, and the upper limit value is changed from the opening degree command value second upper limit value Vd2 to Vdx.

The duty time gradient value Kd and the opening command value time gradient value Kv set based on the initial deviation value Ez are set so that the duty D and the opening command value V are equal to each other so that there is no start shock at the start of control. The value is set to a sufficiently gentle rise. The duty upper limit value Dd and the opening degree command value upper limit value Vd set based on the initial deviation value Ez are different from those of the fork 1 at the start of control from a close distance.
3 is set to a value that does not cause a large lifting speed. These duty time gradient value Kd, opening command value time gradient value Kv, duty upper limit value Dd, and opening command value upper limit value V
d is set based on the data extracted by the actual vehicle test, taking into account the start shock, the stop shock, the time required to reach the target lift Ht, and the like.

Next, the operation and effect of the above configuration will be described with reference to FIGS.
This will be described below. In the present invention, the duty time gradient value K
d, opening degree command value time gradient value Kv, duty upper limit value Dd
And the magnitude of the opening command value upper limit value Vd is changed in accordance with the initial deviation value Ez, and the pattern of the operation curve regarding the deviation value E between the duty upper value Dd and the opening command value upper value Vd is shown in FIGS. Since it is the same as shown, description will be made with reference to FIG. 6 showing only the operation curve of the duty upper limit value Dd.

In FIG. 6, the dotted line shows the relationship between the duty D and the deviation D, which incorporates the duty time gradient value Kd and the duty upper limit value Dd that change according to the magnitude of the initial deviation value Ez. Further, the relationship between the duty D and the deviation value E in a method in which the duty time gradient value Kd and the duty upper limit value Dd are not changed according to the magnitude of the initial deviation value Ez (hereinafter, referred to as a conventional method) is indicated by a solid line.
That is, when the initial deviation value Ez is small, the control is started from the deviation value E indicated by the point P2 and the duty lower limit value Ds. In the case of the dotted line, the duty D changes from the point P2 to K
dx gently as shown by the black arrow
Toward x, the duty D gradually decreases from when the deviation value E becomes smaller than the deceleration point deviation value Ed to reach the duty lower limit value Ds. When the deviation value E becomes smaller than the deviation threshold value Es, the duty D becomes zero. On the other hand, in the case of the solid line, the duty D suddenly changes from the point P2 to the duty upper limit value Dd as indicated by an open arrow, and the duty D gradually decreases when the deviation value E becomes smaller than the deceleration point deviation value Ed. The duty lower limit value Ds is reached. When the deviation value E becomes smaller than the deviation threshold value Es, the duty D becomes zero.

FIG. 7 shows the variation over time of the deviation value E, the duty D, the vibration Vj of the fork 13 according to the conventional method, and the vibration Vh of the fork 13 according to the present invention. Also in this figure, the time change of each state quantity is shown by a solid line in the case of the conventional method and by a dotted line in the case of the present invention, and the effect of the present invention will be described in comparison with the conventional method. When the deviation value E of the conventional method starts control from Ex, D suddenly changes from zero to Dd as shown in FIG. 7B.
The speed of the fork 13 suddenly changes from a zero value, and the vibration of the fork 13 starts to fluctuate greatly as shown in FIG.
As a result, the load placed on the fork 13 dances and the operability is not good. When the deviation value E reaches the deceleration point deviation value Ed, the duty D, which has been a constant value, gradually decreases. At this time, since the speed of the fork 13 changes, the vibration amplitude of the rocking fork 13 does not decrease, and the vibration continues further. When the deviation value E reaches Es, the duty D suddenly changes to a zero value, so that the speed of the fork 13 changes suddenly, and the fork 13 further continues to vibrate. As described above, since the rapid change in the speed is repeated a plurality of times in a short time, the fork 13 may vibrate greatly and cause resonance, and the positioning property is not good.

In the present invention indicated by the dotted line, at the start of the control, the duty D changes from the zero value to the duty lower limit value Ds, but since the duty lower limit value Ds is sufficiently small,
The swing of the fork 13 is minute and rapidly attenuates. Thereafter, the duty D gradually reaches Ddx due to the time gradient value Kdx. Ddx is the duty upper limit value D
Since it is smaller than d, the vibration of the fork 13 is further attenuated. When the deviation value E reaches the deceleration point deviation value Ed, the duty D gradually decreases.
Since the slope at which the duty D gradually decreases with respect to the deviation value E is smaller than that in the conventional method as shown in FIG.
The duty D is determined by a gradual time gradient value as shown in FIG.
Becomes smaller and the deviation value E becomes smaller than the deviation threshold value Es, the duty D becomes zero from the duty lower limit value Ds. In the case of the present invention as well, there are multiple speed changes during a short period of time, but the speed change at the start of control is small, the maximum speed is small, and acceleration and deceleration are performed smoothly, There is no start shock or stop shock, and excellent positioning is obtained.

In the present embodiment, the temporal gradient value and the upper limit value of both the speed command value of the power generating means and the opening command value of the flow control valve are set in accordance with the initial deviation value. Although both the control and the flow control valve are controlled, the same effect can be exerted by control using only the speed command value according to the initial deviation value. Further, similar effects can be exerted by control using only the opening command value according to the initial deviation value. In the present embodiment, the duty time gradient value calculation unit 83
The duty time gradient Kd in is calculated by a mathematical expression represented by a straight line passing through a point (gradient first deviation value E1, duty first gradient value Kd1) and a point (gradient second deviation value E2, duty second gradient value Kd2). However, the gradient first deviation value E1 is smaller than the gradient second deviation value E2, and the duty first gradient value Kd1 is the duty second gradient value Kd.
As long as the constraint condition of being smaller than 2 is satisfied, it is not necessary to be a straight line, a curved line may be used, and a step-like characteristic may be provided. Further, the opening command value time gradient Kv in the opening command value time gradient value calculating unit 84
Is the point (gradient first deviation value E1, opening degree command value first gradient value K
v1) and a point (gradient second deviation value E2, opening degree command value second gradient value Kv2). As long as the constraint condition that the value is smaller than the second gradient value Kv2 is satisfied, it is not necessary to be a straight line, a curved line may be used, or a step-like characteristic may be provided. In addition, the duty upper limit value Dd in the duty upper limit value calculation unit 85 is determined by the point (the upper limit first deviation value e1, the duty first upper limit value Dd1) and the point (the upper limit second deviation value e).
2, the upper limit first deviation value e1 is smaller than the upper limit second deviation value e2, and the first duty upper limit value Dd1 is calculated by an equation represented by a straight line passing through the second duty upper limit value Dd2). If the constraint condition that the duty is smaller than the second upper limit Dd2 is satisfied, the duty does not need to be a straight line, but may be a curve, or may have a step-like characteristic. Further, the opening command value upper limit value Vd in the opening command value upper limit value calculating unit 86 is obtained by calculating the point (upper limit first deviation) by taking the initial deviation value Ez on the horizontal axis and the opening command upper limit value Vd on the vertical axis. The value is calculated by a mathematical expression represented by a straight line passing through the value e1, the opening command value first upper limit value Vd1) and the point (the upper limit second deviation value e2, the opening command value second upper limit value Vd2). As long as the degree command value first upper limit value Vd1 satisfies the constraint condition that it is smaller than the opening degree command value second upper limit value Vd2, the degree command value does not need to be a straight line and may be a curved line. You can do it. In the present embodiment, the hydraulic pump 20 is driven by the electric motor 21 whose rotation speed is controlled by the duty D. However, when the hydraulic pump 20 is driven by the engine, the electronic governor and the electronic fuel injection are driven. The discharge amount of the hydraulic pump 20 may be controlled by an engine rotation speed control device using a device or the like.

According to the present invention, the time gradient value and the upper limit value of the speed command value for commanding the magnitude of the power generated by the power generating means for driving the fork in accordance with the initial deviation value at the start of the automatic lift control are set. are doing. When the initial deviation value is small, the speed command value is gradually increased by a small temporal gradient value compared to when the initial deviation value is large. Further, the upper limit value of the speed command value is set small. Further, a time gradient value and an upper limit value of the opening command value to the flow control valve for controlling the power of the lift cylinder are set. When the initial deviation value is small, the opening command value is gradually increased by a small temporal gradient value compared to when the initial deviation value is large. further,
The upper limit of the opening command value is set small. When the initial deviation value is small, the speed command value and the opening degree command value gradually increase gradually with time, so that the fork does not vibrate greatly at the time of starting, and the starting shock of the fork at the start of the positioning control can be reduced. Also, when the initial deviation value is small, the upper limit value of the speed command value and the opening command value is set smaller than when the initial deviation value is large, so that the deviation value becomes smaller than the deceleration point deviation value. The speed command value and the opening command value gradually decrease gradually until they reach their lower limit values as compared with when the initial deviation value is large. As a result, the fork slowly decelerates and stops. As a result, the starting shock and the stopping shock can be reduced, so that excellent positioning can be obtained without the fork being largely shaken by resonance or the like.

[Brief description of the drawings]

FIG. 1 is a hardware configuration diagram according to the present invention.

FIG. 2 is a configuration diagram of a controller according to the present invention.

FIG. 3 is an explanatory diagram of a duty for each magnitude of an initial deviation value.

FIG. 4 is an explanatory diagram of an opening command value for each magnitude of an initial deviation value.

FIG. 5 is an explanatory diagram of a temporal change in a deviation value, a duty, and an opening command value for each magnitude of an initial deviation value.

FIG. 6 is a comparison diagram of duty when control is performed according to the magnitude of an initial deviation value and when control is not performed.

FIG. 7 is an explanatory diagram of a temporal change of a deviation value, a duty, and a vibration of a fork when control is performed according to the magnitude of an initial deviation value and when control is not performed.

FIG. 8 is an explanatory diagram of a forklift as an example of an industrial vehicle.

FIG. 9 is an explanatory diagram of a conventional technique for automatic lifting control.

[Explanation of symbols]

11: outer rail, 12: inner rail, 13: fork, 14: lift cylinder, 16: solenoid proportional valve, 20
... hydraulic pump, 21 ... electric motor, 22 ... lift lever, 23 ... lift sensor, 24 ... lever operation amount detector, 2
5 target lift setting means, 26 controller, 70 deviation value calculation unit, 71 duty calculation unit, 72 output permission determination unit, 73 opening degree command value calculation unit, 74 lever command value calculation unit, 79 ··························································································································
85: Duty upper limit value calculating unit, 86: Opening command value upper limit calculating unit, 87: Duty generator, 88: Opening command value generator, 89: Duty minimum value determining unit, Ht: Target lift, H ... Lift height, E: deviation value, Ed: deceleration point deviation value, Es
... Deviation threshold value, Ez: Initial deviation value, Sa: Automatic command signal,
Lev: lever operation amount, LS: lever operation signal, Sv:
Electromagnetic proportional valve command value, V: opening command value, Vd: opening command value upper limit value, Vs: opening command value lower limit value, Dm: motor duty command value, D: duty, Dd: duty upper limit value, Ds ... Duty lower limit value, Kv: Opening command value time gradient value, Kd: Duty time gradient value.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Norihiko Eda 110 Yokokura Nitta, Koyama City, Tochigi Prefecture Komatsu Forklift Co., Ltd. Tochigi Plant F term (reference) 3F333 AA02 AB18 BA02 BD02 DA05 FB05 FD01

Claims (3)

[Claims] 1. A target lift setting means for setting a target lift of a fork, a lift sensor for detecting a lift of a fork, a power generating means whose rotation speed is controlled by a speed command, and a power generating means. A driven hydraulic pump, a lift cylinder for controlling the lift of the fork, and a flow rate disposed between the hydraulic pump and the lift cylinder for controlling the amount of oil to the lift cylinder based on an opening degree command for setting an opening area. When the positional deviation between the target lift of the fork set by the target lift setting means and the lift detected by the lift sensor is larger than a predetermined deceleration point deviation, the control valve outputs a predetermined upper limit value. When the value is smaller than the predetermined deceleration point deviation value, the speed command value of the power generation means and the speed command value are calculated by a calculation curve set to output a value that gradually decreases from the upper limit value to the predetermined lower limit value according to the position deviation. And a controller for calculating and outputting at least one of the opening command values of the flow control valve and the controller for controlling the positioning of the fork. The smaller of the command value that gradually increases from the start of control based on the temporal gradient value according to the magnitude and the command value that is computed by a computation curve having an upper limit value that depends on the magnitude of the initial deviation value An automatic lift control device for a forklift, which outputs a speed command value of a power generation means. 2. A target lift setting means for setting a target lift of a fork, a lift sensor for detecting a lift of a fork, a power generator having a rotational speed controlled by a speed command, and a power generator. A driven hydraulic pump, a lift cylinder for controlling the lift of the fork, and a flow rate disposed between the hydraulic pump and the lift cylinder for controlling the amount of oil to the lift cylinder based on an opening degree command for setting an opening area. When the positional deviation between the target lift of the fork set by the target lift setting means and the lift detected by the lift sensor is larger than a predetermined deceleration point deviation, the control valve outputs a predetermined upper limit value. When the value is smaller than the predetermined deceleration point deviation value, the speed command value of the power generation means and the speed command value are calculated by a calculation curve set to output a value that gradually decreases from the upper limit value to the predetermined lower limit value according to the position deviation. And a controller for calculating and outputting at least one of the opening command values of the flow control valve and the controller for controlling the positioning of the fork. The smaller of the command value that gradually increases from the start of control based on the temporal gradient value according to the magnitude and the command value that is computed by a computation curve having an upper limit value that depends on the magnitude of the initial deviation value An automatic lift control device for a forklift, which outputs an opening command value of a flow control valve. 3. A fork height setting means for setting a fork target height, a fork height sensor for detecting a fork height, a power generation means for controlling a rotation speed by a speed command, and a power generation means. A driven hydraulic pump, a lift cylinder for controlling the lift of the fork, and a flow rate disposed between the hydraulic pump and the lift cylinder for controlling the amount of oil to the lift cylinder based on an opening degree command for setting an opening area. When the positional deviation between the target lift of the fork set by the target lift setting means and the lift detected by the lift sensor is larger than a predetermined deceleration point deviation, the control valve outputs a predetermined upper limit value. When the value is smaller than the predetermined deceleration point deviation value, the speed command value of the power generation means and the speed command value are calculated by a calculation curve set to output a value that gradually decreases from the upper limit value to the predetermined lower limit value according to the position deviation. And a controller for calculating and outputting at least one of the opening command values of the flow control valve and the controller for controlling the positioning of the fork. The smaller of the command value that gradually increases from the start of control based on the temporal gradient value according to the magnitude and the command value that is computed by a computation curve having an upper limit value that depends on the magnitude of the initial deviation value An automatic lift control device for a forklift, which outputs a speed command value of a power generation means and an opening command value of a flow control valve.