JP3116648B2 - Hydraulic control device for cargo handling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for cargo handling, and more particularly to a hydraulic control device for cargo handling provided with a stepping motor for controlling a spool of a control valve for cargo handling.

[0002]

2. Description of the Related Art Conventionally, forklifts in industrial vehicles are provided with control valves. By adjusting the amount and direction of the spool movement of the control valve, the supply amount and supply direction of the hydraulic oil supplied to the hydraulic cylinder are determined. Also, in recent years, a cargo handling hydraulic control device that controls a spool of a control valve by a stepping motor has been proposed. This hydraulic control device for cargo handling is shown in FIG.

The loading lever 51 is provided with a potentiometer 52 for detecting the operation amount of the loading lever 51. The potentiometer 52 detects the operation amount of the loading lever 51 and outputs it to the controller 53. The controller 53 controls the drive of the stepping motor 54 based on the operation amount of the cargo handling lever 51, moves the spool 56 of the control valve 55, and stops at the target position corresponding to the operation amount of the cargo handling lever 51.

Hydraulic oil is supplied to a hydraulic cylinder (not shown) in accordance with the position of the spool 56, and the fork moves up and down. At this time, the stepping motor 54
Is driven and controlled at 500 pps (unit: the number of pulses at which the stepping motor 54 operates per second) previously obtained by an experiment or the like. The stepping motor 54 is controlled by a drive voltage (constant voltage) supplied from a battery (not shown).

[0005]

The spool 5
In some cases, the sliding resistance becomes large, making it difficult to slide. In this case, the force for operating the spool 56 increases.

However, the stepping motor 54 is always controlled by the controller 53 at a driving frequency of 500 pps. Therefore, the torque generated in the stepping motor 54 does not change. Therefore, when the torque required to operate the spool 56 having the increased sliding resistance exceeds the torque of the stepping motor 54, there is a problem that the stepping motor 54 steps out.

When the stepping motor 54 loses synchronism, the spool 56 remains at the neutral position, so that the amount of hydraulic oil supplied to the hydraulic cylinder cannot be controlled.
Accordingly, there is a problem that the hydraulic cylinder cannot be controlled even when the cargo handling lever 51 is operated, and the cargo handling work cannot be performed.

An object of the present invention is to provide a hydraulic control device for cargo handling which can increase the torque generated in a stepping motor and prevent the stepping motor from stepping out even if the sliding resistance of the spool of the control valve increases. Is to do.

[0009]

According to the first aspect of the present invention, there is provided a hydraulic control device for a cargo handling system, wherein a hydraulic cylinder is operated by operating a spool of a control valve by a stepping motor in accordance with an operation amount of a cargo handling lever. A lever detecting means for detecting an operation amount of the cargo handling lever, a detecting means for detecting an amount of movement of the spool or a rotation amount of a stepping motor, and a detecting means for the cargo handling lever at that time based on the lever detecting means and the detecting means. Determining means for determining whether the operation amount corresponds to the movement amount of the spool or the rotation amount of the stepping motor; and, based on the determination result from the determination means, the operation amount of the loading / unloading lever and the movement amount or stepping of the spool. Control to increase the torque of the stepping motor when the rotation amount of the motor does not correspond A speed calculating means for calculating a degree, and summarized in that and a motor control means for controlling the stepping motor based on the control speed obtained by said speed calculating means.

Further, in the invention according to the second aspect, a hydraulic control device for cargo handling which operates a hydraulic cylinder for raising and lowering a fork by operating a spool of a control valve by a stepping motor in accordance with an operation amount of a cargo handling lever. , A lever detecting means for detecting an operation amount of the cargo handling lever, a lifting height detecting means for detecting a lifting height of the fork, and a movement for calculating a moving speed of the fork based on a detection signal from the lifting height detecting means. Speed calculation means,
Determining means for determining whether or not the operation amount of the cargo handling lever at that time corresponds to the moving speed of the fork based on the lever detecting means and the moving speed calculating means; and based on the determination result from the determining means. When the operation amount of the loading lever and the moving speed of the fork do not correspond to each other, a speed calculating unit that calculates a control speed for increasing the torque of the stepping motor, and a control speed obtained by the speed calculating unit. The gist of the invention is to provide a motor control means for controlling the stepping motor.

[0011]

According to the first aspect of the present invention, the lever detecting means detects the operation amount of the cargo handling lever, and the detecting means detects the amount of movement of the spool or the amount of rotation of the stepping motor.
The determining means determines whether the moving amount of the spool or the rotating amount of the stepping motor corresponds to the operation amount of the cargo handling lever, and if not, the speed calculating means increases the torque of the stepping motor. Is calculated. The motor control means drives and controls the stepping motor based on the control speed.

According to the second aspect of the present invention, the lever detecting means detects the operation amount of the cargo handling lever. The lift detecting means detects the lift position of the fork, and the moving speed calculating means calculates the moving speed of the fork based on the detection result. The determining means determines whether or not the moving speed of the fork corresponds to the operation amount of the cargo handling lever, and if not, the speed calculating means calculates a control speed for increasing the torque of the stepping motor. . The motor control means drives and controls the stepping motor based on the control speed.

[0013]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. As shown in FIG. 1, the cargo handling lever 1 is provided in a driver seat of a forklift (not shown). The loading lever 1 is connected to a potentiometer 2 for detecting the operation amount (angle) thereof. The potentiometer 2 is connected to the controller 3.

The forklift is provided with a hydraulic cylinder 5 for raising and lowering the fork 4. The hydraulic cylinder 5 is connected to a control valve 6. Hydraulic oil is supplied to the control valve 6 by a hydraulic pump 8 rotationally driven by a cargo pump motor 7. The control valve 6 is provided with a spool 9. By sliding the spool 9 in the vertical direction, the hydraulic oil supplied from the hydraulic pump 8 is supplied to the hydraulic cylinder 5, and the fork 4 is moved up and down.

That is, hydraulic oil is supplied to the hydraulic cylinder 5 in an amount corresponding to the moving position of the spool 9. When the spool 9 is in the neutral position, no hydraulic oil is supplied to the hydraulic cylinder 5, and the fork 4 is held at that position. The hydraulic cylinder 5 is supplied with hydraulic oil in an amount corresponding to the moving position of the spool 9, and the fork 4 is moved up and down at a speed corresponding to the amount.

Further, the control valve 6 is provided with a spool sensor 10. The spool sensor 10 detects the amount of movement of the spool 9 and outputs a voltage corresponding to the amount of movement to the controller 3.

The spool 9 has a stepping motor 1
1 are connected via an arm 12. The movement of the spool 9 is controlled by rotating the stepping motor 11. The driving of the stepping motor 11 is controlled by the controller 3. In the present invention, a driving voltage (12 V) is supplied to the stepping motor 11 from a battery (not shown).

Next, an electrical configuration of the hydraulic control device for cargo handling will be described. The controller 3 is a central processing unit 13
(Hereinafter referred to as CPU), read-only memory 14 (hereinafter referred to as ROM), readable and writable memory 1
5 (hereinafter referred to as RAM), A / D converters 16 and 17
And a motor drive circuit 18.

The potentiometer 2 provided on the loading lever 1 is connected to the A / D converter 16. A /
The D converter 16 A / D converts the operation direction and the operation angle with a predetermined resolution as an operation amount of the cargo handling lever 1 detected by the potentiometer 2 and outputs the result to the CPU 13.

The spool sensor 10 provided in the control valve 6 is connected to the A / D converter 17. The A / D converter 17 A / D converts a voltage corresponding to the moving position of the spool 9 detected by the spool sensor 10 with a predetermined resolution and outputs the voltage to the CPU 13.

When the spool 9 is at the neutral position,
The spool sensor 10 outputs 2.5 V to the controller 3. When the spool 9 moves up and reaches the uppermost position, the spool sensor 10 outputs 5 V to the controller 3. When the spool 9 descends and reaches the lowermost position, the spool sensor 10 outputs 0 V to the controller 3.

The ROM 14 stores an operation amount-step number map for controlling the stepping motor 11 as shown in FIG. The CPU 13 reads the A / D conversion value of the output value as the operation amount of the cargo handling lever 1 and the target number of steps of the stepping motor 11 as the position of the spool 9 from the operation amount-step number map. Then, the CPU 13 stores the target step number read from the ROM 14 in the RAM 15, and controls the drive of the stepping motor 11 to a position corresponding to the target step number.

In this operation amount-step number map, a dead zone is provided near the neutral position of the cargo handling lever 1, so that the stepping motor 11 does not rotate if the cargo handling lever 1 is slightly moved from the neutral position. I have.
When the operation amount of the cargo handling lever 1 passes through the dead zone, the target number of steps of the stepping motor 11 increases in accordance with the operation amount. Further, in a region where the operation amount of the cargo handling lever 1 is large, the stepping motor 11 rotates to the maximum rotation position and slides the spool 9.

Further, as shown in FIG.
At a driving voltage of 2 V, a driving frequency-torque map indicating torque obtained with respect to the driving frequency of the stepping motor 11 is stored. In the present embodiment, the stepping motor 11 is driven at a driving frequency of 500 pps obtained in advance through experiments or the like. In that case, a torque T1 is generated in the stepping motor 11.

The CPU 13 detects the operation amount of the cargo handling lever 1 by the potentiometer 2 and reads out the target number of steps of the stepping motor 11 from the operation amount-step number map shown in FIG. 4 based on the detection result. The CPU 13 rotates the stepping motor 11 via the motor drive circuit 18 according to the target number of steps, and slides the spool 9. Further, the CPU 13 detects the amount of movement of the spool 9 by the spool sensor 10.

Further, based on detection signals from the potentiometer 2 and the spool sensor 10, the CPU 13 determines whether the operation amount of the cargo handling lever 1 at that time corresponds to the movement amount of the spool 9.

When the CPU 13 determines that the movement amount of the spool 9 corresponds to the operation amount of the cargo handling lever 1, the CPU 13 controls the drive of the stepping motor 11 at the drive frequency 500 pps stored in the ROM 14. .

On the other hand, if the CPU 13 determines that the movement amount of the spool 9 is smaller than the operation amount of the cargo handling lever 1, the CPU 13 determines that the sliding resistance of the spool 9 has increased. Then, the CPU 13 determines that a large torque for sliding the spool 9 is necessary, and changes the drive frequency for controlling the drive of the stepping motor 11. That is, the CPU 13 determines the driving frequency −
The driving frequency is changed from 500 pps to 200 pps based on the torque map. Therefore, a torque T2 larger than the torque T1 generated when the stepping motor 11 is driven and controlled at 500 pps is generated. The spool 9 whose sliding resistance has been increased by the torque T2 generated by the driving frequency of 200 pps can be sufficiently slid.

A control program for the CPU 13 is stored in the ROM 14. This control program includes the main control shown in FIG. 2 and the interrupt control shown in FIG. In the main control, the CPU 13 reads the operation amount of the cargo handling lever 1 via the A / D converter, and calculates the target number of steps of the stepping motor 11 according to the operation amount. In the main control, the CPU 13 detects the amount of movement of the spool 9 by the spool sensor 10 and calculates a drive frequency as a control speed of the stepping motor 11 based on a result of comparing the detection result with the operation amount of the cargo handling lever 1. I do.

In the interrupt control, the CPU 13 drives the stepping motor 11 by one step via the motor drive circuit 18 and controls the stepping motor 11 to reach the target number of steps.

The calculation result of the CPU 13 is temporarily stored in the RAM 15. The RAM 15 stores an interrupt cycle of the interrupt control. Interrupt control
The interrupt cycle is written to a predetermined address, and the stepping motor 11 is started at the interrupt cycle. Each time the step is performed, the stepping motor 11 is moved forward or backward by one step.

The interrupt cycle is determined by the drive frequency of the stepping motor 11. For example, if the stepping motor 11 is driven at 500 pps, the interrupt cycle is 2 ms. If the stepping motor 11 is driven at 200 pps, the interrupt cycle is 5 ms.

Motor drive circuit 1 connected to CPU 13
8 is connected to a stepping motor 11. The motor drive circuit 18 outputs a pulse corresponding to the drive frequency corresponding to the forward or reverse rotation direction output from the CPU 13. Therefore, the stepping motor 11 rotates one step in the forward direction or the reverse direction.

Next, the operation of the hydraulic control apparatus for cargo handling configured as described above will be described with reference to the flowcharts of FIGS. First, according to the flowchart of FIG.
The main control of the PU 13 will be described.

When the CPU 13 starts the main control, the CPU 13 proceeds to step 1 (hereinafter, step is simply referred to as S).
5 and the stepping motor 11 stored in the
The initialization of the target position and the like is performed. The interrupt cycle is set to a predetermined cycle (2 ms in this embodiment). The target position is set to the neutral position of the spool 9 as the initial position of the stepping motor 11.

Next, the CPU 13 determines in S2 that the loading lever 1
Is detected from the potentiometer 2. And
The CPU 13 reads out the target number of steps of the stepping motor 11 in accordance with the operation amount of the cargo handling lever 1 from the operation amount-step number map stored in the ROM 14 in step S3, and sets
Store it in AM15. The CPU 13 controls the drive of the stepping motor 11 to a position corresponding to the target number of steps.

On the other hand, in S4, the CPU 13 determines the amount of movement of the spool 9 by the rotation of the stepping motor 11 by A / A.
The data is read via the D converter 17. And CPU1
3 compares the operation amount of the cargo handling lever 1 at that time with the movement amount of the spool 9 in S5. When the movement amount of the spool 9 corresponds to the operation amount of the cargo handling lever 1, the CPU
13 sets the drive frequency of the stepping motor 11 to 500 pps in S6. Therefore, the torque generated in the stepping motor 11 is T1. At this time, RAM
The interrupt cycle stored in No. 15 is 2 ms.

Next, the CPU 13 waits for 10 ms to elapse in S8. After 10 ms, the CPU 1
No. 3 repeats the processing after S2. Therefore, CPU1
3 performs the processing from S2 to S8 every 10 ms, and sets the target number of steps of the stepping motor 11 according to the operation amount of the cargo handling lever 1 for each cycle. CPU 13
Sets the interrupt cycle of the interrupt control for step driving the stepping motor 11 based on the result of comparing the amount of movement of the spool 9 and the amount of operation of the cargo handling lever 1.

Next, according to the flowchart of FIG.
The interrupt control of the PU 13 will be described. When the interrupt control is started, the CPU 13 checks the position of the stepping motor 11 in S9. If the stepping motor 11 has not reached the target position determined in S3 of the main control, the CPU 13 advances the stepping motor 11 by one step in the forward or reverse direction in S10. If the stepping motor 11 has already reached the target position at S9, the CPU 13 holds the stepping motor 11 at the target position at S11.

Next, the CPU 13 reads the next interrupt cycle from the RAM 15 at S12, sets it to a predetermined address, and ends the interrupt control. Accordingly, the interrupt control of the stepping motor 11 is started in accordance with the interrupt cycle stored in the RAM 15, and the stepping motor 11 is driven to rotate one step at a time in the interrupt cycle in the forward or reverse direction.

As a result, the spool 9 slides in accordance with the operation amount of the cargo handling lever 1, the hydraulic oil is supplied to the hydraulic cylinder 5, and the fork 4 rises. On the other hand, in S5, when the movement amount of the spool 9 does not correspond to the operation amount of the cargo handling lever 1 at this time, that is, when the movement amount of the spool 9 is smaller than the operation amount of the cargo handling lever 1, the CPU 13 It is determined that the sliding resistance has increased.

Then, the CPU 13 determines in S7 that the ROM 14
The drive frequency 200p of the stepping motor 11 which can sufficiently slide the spool 9 having the increased sliding resistance based on the drive frequency-torque map stored in
Change to ps. The interrupt cycle at this time is 5 ms. Then, the CPU 13 stores the interrupt cycle in the RAM
15 is stored. Since the CPU 13 controls the rotation of the stepping motor 11 in this interrupt cycle, a torque T2 is generated in the stepping motor 11. As a result, the spool 9 with increased sliding resistance can be slid.

Accordingly, in the hydraulic control apparatus for cargo handling of the present embodiment, when the sliding resistance of the spool 9 in the control valve 6 becomes large and the operation amount of the cargo handling lever 1 does not correspond to the movement amount of the spool 9, the CPU 13 The drive frequency of the stepping motor 11 is changed to increase the torque. As a result, the spool 9 having increased sliding resistance
Can be reliably operated, so that step-out of the stepping motor 11 can be prevented and cargo handling work can be performed.

Next, a second embodiment will be described with reference to FIGS. The description of the same configuration as that of the first embodiment will be omitted by using the reference numerals of the first embodiment, and a new configuration will be described.

As shown in FIG. 6, a bracket 19 is fixed to the fork 4. A wire 21 of a height sensor 20 is connected to the bracket 19 via a pulley 22. The lift sensor 20 detects the lift position of the fork 4 and outputs the detected position to the CPU 13 via the A / D converter 17.

Since the moving speed and moving direction of the fork 4 correspond to the operation amount and operation direction of the cargo handling lever 1, C
The PU 13 calculates the moving speed and the moving direction of the fork 4 based on the detection result of the height sensor 20.

Next, the operation of the cargo handling hydraulic control device configured as described above will be described with reference to the flowchart of FIG. Note that the interrupt control of the CPU 13 for operating the stepping motor 11 by one step is the same as that of the first embodiment, and the description is omitted.

When the main control is started, the CPU 13 executes S
At 21, the initialization of the interrupt cycle and the target position of the stepping motor 11 stored in the RAM 15 is performed. The interrupt cycle is set to a predetermined cycle (2 ms in this embodiment). The target position is set to the neutral position of the spool 9 as the initial position of the stepping motor 11.

Next, the CPU 13 detects the operation amount of the cargo handling lever 1 from the potentiometer 2 in S22. Then, the CPU 13 stores the target number of steps of the stepping motor 11 in accordance with the operation amount of the loading
It is read from the manipulated variable-step number map stored in 14 and stored in the RAM 15. The CPU 13 controls the drive of the stepping motor 11 to a position corresponding to the target number of steps.

On the other hand, the CPU 13 reads the lift signal of the fork 4 via the A / D converter 17 in S24, and calculates the moving speed and direction of the fork 4 in S25. Then, in S26, the CPU 13 compares the moving speed and the moving direction of the fork 4 at that time with the operation amount and the operation direction of the cargo handling lever 1. When the moving speed and the moving direction of the fork 4 correspond to the operation amount and the operation direction of the cargo handling lever 1, the CPU 13 sets the driving frequency of the stepping motor 11 to 500 pps in S27. The interrupt cycle at this time is 2 ms, and the CPU 13 stores this interrupt cycle in the RAM 15. When the rotation of the stepping motor 11 is controlled in this interrupt cycle, a torque T1 is generated in the stepping motor 11.

When the moving speed and the moving direction of the fork 4 do not correspond to the operation amount and the operation direction of the cargo handling lever 1 in S26, for example, when the moving speed of the fork 4 is smaller than the operation amount of the cargo handling lever 1, the CPU 13 It is determined that the sliding resistance of the spool 9 has become larger than usual.

Then, the CPU 13 determines in S28 that the ROM 1
4 based on the driving frequency-torque map stored in
The driving frequency 200 of the stepping motor 11 enables the spool 9 having the increased sliding resistance to slide sufficiently.
Set to pps. The interrupt cycle at this time is 5 ms
Becomes Then, the CPU 13 determines this interrupt cycle as RA
Store it in M15. Since the CPU 13 controls the rotation of the stepping motor 11 in this interrupt cycle, a torque T2 is generated in the stepping motor 11. As a result, the spool 9 with increased sliding resistance can be slid.

Therefore, in the hydraulic control apparatus for cargo handling of the present embodiment, the sliding resistance of the spool 9 in the control valve 6 becomes large, and the operation amount and operation direction of the cargo handling lever 1 and the moving speed and moving direction of the fork 4 are reduced. If not, the CPU 13 changes the drive frequency of the stepping motor 11 to increase the torque. As a result, it is possible to reliably operate the spool 9 having the increased sliding resistance, so that step-out of the stepping motor 11 can be prevented and cargo handling work can be performed. In this case, the driving frequency of the stepping motor 11 is changed to
Next, a third embodiment will be described with reference to FIGS.
The description of the parts having the same configuration as the first embodiment will be described in the first embodiment.
The description will be omitted using the reference numerals of the embodiment, and a new configuration will be described.

As shown in FIG. 8, the stepping motor 1
A disk 24 is fixed to one drive shaft 23 so as to rotate integrally with the drive shaft 23. The disk 24 has a recess 25 on the outer periphery.
Are formed. Switches 26 and 27 are provided in the recess 25 so that they are turned off (open) when the cargo handling lever 1 is in the neutral position, that is, when the spool 9 is in the neutral position. When the stepping motor 11 rotates, the switches 26 and 27 rotate the disk 2 fixed to the drive shaft 23.
4 turns on (closes).

When the stepping motor 11 rotates clockwise in FIG. 8 in accordance with the operation of the loading lever 1, the spool 9 of the control valve 6 raises the fork 4 by the arm 12 fixed to the drive shaft 23 of the stepping motor 11. To slide. At this time, the switches 26 and 2
7 turns on the switch 27 after the switch 26 is turned on. When the loading lever is returned to the neutral position, switch 2
After the switch 7 is turned off, the switch 26 is turned off.

When the stepping motor 11 rotates counterclockwise in FIG. 8 in accordance with the operation of the loading lever 1, the arm 1 fixed to the drive shaft 23 of the stepping motor 11 is rotated.
2, the spool 9 of the control valve 6 slides in the direction of lowering the fork 4. At this time, switch 2
Switches 6 and 27 switch 2 after switch 27 is turned on.
6 turns on. When the loading lever is returned to the neutral position, the switch 26 is turned off after the switch 27 is turned off.

The switches 26 and 27 are connected to the C
The CPU 13 is connected to the PU 13 and switches 26 and 27
Of the spool 9 is detected, and whether the spool 9 is raised or lowered is detected. Further, the CPU 13 operates the switch 2
It is detected that the spool 9 is at the neutral position by turning off the spools 6 and 27.

Next, the operation of the hydraulic control apparatus for cargo handling configured as described above will be described with reference to the flowchart of FIG. Note that the interrupt control of the CPU 13 for operating the stepping motor 11 by one step is the same as that of the first embodiment, and the description is omitted.

When the CPU 13 starts the main control, S
At 31, an interrupt cycle stored in the RAM 15 and a target position of the stepping motor 11 are initialized. The interrupt cycle is set to a predetermined cycle (2 ms in this embodiment). The target position is set to the neutral position of the spool 9 as the initial position of the stepping motor 11.

Next, the CPU 13 detects the operation amount of the cargo handling lever 1 from the potentiometer 2 in S32. Then, the CPU 13 stores the target number of steps of the stepping motor 11 in accordance with the operation amount of the loading
It is read from the manipulated variable-step number map stored in 14 and stored in the RAM 15. The CPU 13 controls the drive of the stepping motor 11 to a position corresponding to the target number of steps.

On the other hand, the CPU 13 reads the state of the switches 26 and 27 in S34. When the cargo handling lever 1 is tilted from the neutral position, the CPU 13 checks the direction in which the stepping motor 11 has turned in the order in which the switches 26 and 27 are turned on. For example, when the switch 27 is turned on after the switch 26 is turned on, it can be understood that the stepping motor 11 has turned clockwise in FIG. When the switch 26 is turned on after the switch 27 is turned on, it can be understood that the stepping motor 11 has rotated in the counterclockwise direction in FIG. Further, when the switches 26 and 27 are both off, it is understood that the stepping motor 11 does not rotate in any direction, that is, is in the neutral position.

Then, the CPU 13 compares the operation direction of the cargo handling lever 1 with the rotation direction of the stepping motor 11 in S35. If the rotation direction of the stepping motor 11 corresponds to the operation direction of the cargo handling lever 1, the CPU
13 sets the driving frequency of the stepping motor 11 to 500 pps in S36. The interrupt cycle at this time is 2
ms, and the CPU 13 sets this interrupt cycle in the RAM 1
5 is stored. When the CPU 13 controls the rotation of the stepping motor 11 in this interrupt cycle, a torque T1 is generated in the stepping motor 11.

In step S35, if the rotation direction of the stepping motor 11 does not correspond to the operation direction of the cargo handling lever 1, for example, if both the switches 26 and 27 are not turned off even if the cargo handling lever 1 is returned to the neutral position, the CPU 13 It is determined that the sliding resistance of the spool 9 has increased.

Then, the CPU 13 determines in S37 that the ROM 1
4 based on the driving frequency-torque map stored in
The driving frequency 200 of the stepping motor 11 can sufficiently slide the spool 9 having increased sliding resistance.
Change to pps. The interrupt cycle at this time is 5 ms
Becomes Then, the CPU 13 determines this interrupt cycle as RA
Store it in M15. When the CPU 13 controls the rotation of the stepping motor 11 in this interrupt cycle, a torque T2 is generated in the stepping motor 11. As a result, the spool 9 with increased sliding resistance can be slid.

Accordingly, in the hydraulic control apparatus for cargo handling of the present embodiment, when the sliding resistance of the spool 9 in the control valve 6 becomes large and the operation amount of the cargo handling lever 1 does not correspond to the rotation direction of the stepping motor 11, CPU1
Reference numeral 3 changes the drive frequency of the stepping motor 11 to increase the torque. As a result, the spool 9 having increased sliding resistance can be reliably operated.
Cargo handling can be performed while preventing the stepping motor 11 from stepping out.

The present invention is not limited to the above embodiment, but may be made as follows without departing from the spirit of the present invention. (1) In the above embodiment, the drive frequency of the stepping motor 11 is set to 200 pps, which is a value obtained in advance through experiments, but may be set to any value as needed. Further, the driving frequency of the stepping motor 11 is changed from 500 pps to 20.
Although the embodiment is changed to 0 pps, the drive frequency may be variably changed to obtain various torques.

(2) In the above embodiment, the hydraulic cylinder 5 for lifting and lowering the fork is used. However, the present invention may be applied to another hydraulic cylinder for reach and tilt. Further, the present invention may be applied to a cargo handling vehicle other than a forklift.

(3) In the third embodiment, the two switches 26 and 27 are used to detect the neutral position or the rotating direction of the stepping motor 11, but the detection is performed using one or a plurality of switches. You may do so. Further, the rotation position and the rotation direction of the stepping motor 11 may be detected using a rotary encoder or the like.

(4) In the third embodiment, the disk 24 is provided on the drive shaft 23 of the stepping motor 11 to detect the neutral position or the amount of rotation of the stepping motor 11. The amount of rotation may be detected.

[0070]

According to the hydraulic control device for cargo handling according to the first aspect, the amount of movement of the spool or the amount of rotation of the stepping motor is detected by the detecting means, and the detection result and the cargo handling detected by the lever detecting means are detected. Compare the lever operation amount. When the movement amount of the spool or the rotation amount of the stepping motor does not correspond to the operation amount of the cargo handling lever, the control speed of the torque of the stepping motor is changed by the speed calculating means to increase the torque generated in the stepping motor. Therefore, there is an excellent effect that the stepping motor can be prevented from stepping out.

According to the second aspect of the present invention, the lift position of the fork is detected by the lift detecting means, and the fork position calculated by the moving speed calculating means based on the detection result. The moving speed is compared with the operation amount of the cargo handling lever detected by the lever detecting means. If the moving speed of the fork does not correspond to the operation amount of the cargo handling lever, the speed calculation means changes the control speed of the torque of the stepping motor to increase the torque generated in the stepping motor. This has an excellent effect that the key can be prevented from being adjusted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hydraulic control device for cargo handling according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing main control according to the first embodiment of the present invention.

FIG. 3 is a flowchart of interrupt control for operating a stepping motor by one step.

FIG. 4 is a characteristic diagram illustrating a relationship between an operation amount of a cargo handling lever and a target number of steps of a stepping motor.

FIG. 5 is a characteristic diagram showing a relationship between a driving frequency of a stepping motor and a generated torque.

FIG. 6 is a configuration diagram of a hydraulic control device for cargo handling according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing main control according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram of a stepping motor according to a third embodiment of the present invention.

FIG. 9 is a flowchart showing main control according to a third embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional hydraulic control device for cargo handling.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Unloading lever, 2 ... Potentiometer as lever detecting means, 4 ... Fork, 5 ... Hydraulic cylinder, 6 ... Control valve, 9 ... Spool, 10 ... Spool sensor as detecting means, 11 ... Stepping motor, 13 ...
CPU as judgment means, speed calculation means, motor control means and moving speed calculation means, 20... Lift sensor as lift detection means, 26, 27... Switches as detection means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-224000 (JP, A) JP-A-4-275097 (JP, A) JP-A-2-151298 (JP, A) JP-A-61- 217499 (JP, A) JP-A-61-211300 (JP, A) JP-A-61-229795 (JP, A) JP-A-3-40799 (JP, A) JP-A-4-46098 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B66F 9/24

Claims (2)

(57) [Claims] 1. A loading hydraulic control device for operating a hydraulic cylinder by operating a spool of a control valve by a stepping motor in accordance with an operation amount of a loading lever, wherein a lever detecting means for detecting an operation amount of the loading lever. Detecting means for detecting the amount of movement of the spool or the amount of rotation of the stepping motor; and the amount of operation of the cargo handling lever and the amount of movement of the spool or the amount of rotation of the stepping motor at that time based on the lever detecting means and the detecting means. A stepping motor for determining whether or not the amount of operation of the cargo handling lever and the amount of movement of the spool or the amount of rotation of the stepping motor correspond to each other based on the determination result from the determining means. Speed calculating means for calculating a control speed for increasing the torque of the vehicle; Hydraulic control device for handling with a motor control means for controlling the stepping motor based on the control speed which is determined by. 2. A loading hydraulic control device for operating a hydraulic cylinder for raising and lowering a fork by operating a spool of a control valve by a stepping motor in accordance with an operation amount of a loading lever, wherein the operation amount of the loading lever is detected. Lever detecting means for detecting, fork height detecting means for detecting the height of the fork, moving speed calculating means for calculating the moving speed of the fork based on a detection signal from the height detecting means, the lever detecting means, Judgment means for judging whether or not the operation amount of the cargo handling lever at that time corresponds to the movement speed of the fork based on the movement speed calculation means, and the operation amount of the cargo handling lever based on the judgment result from the judgment means If the moving speed of the fork does not correspond to the moving speed of the fork, a control speed for increasing the torque of the stepping motor is calculated. And speed calculating means, a hydraulic control device for a cargo handling with a motor control means for controlling the stepping motor based on the control speed obtained by said speed calculating means.