JPH05231404A - Cargo handling hydraulic control device for industrial vehicle - Google Patents

Abstract

PURPOSE:To enable adjustment to be easily made for starting the operation of cargo handling hydraulic equipment by causing an opening control means to output a proportionally increasing instruction means, when an operation means is operated to generate setting control input in state where matching mode is set to adjust the operation start point of the cargo handling hydraulic equipment. CONSTITUTION:When an ignition switch is operated, CPU 11 is caused to discriminate whether matching adjustment mode is set by a setting switch 17. If affirmative, a lift cylinder 5 is caused to operate on hydraulic oil supplied through a control valve 4 controlled for open and close operation with proportionally increasing drive current from a constant current amplifier 13, when a lift lever 1 is set at the predetermined adjusting control input. Also, the drive current at the operation start of the lift cylinder 5 is saved in EPROM 10, and when the lift lever 1 is moved to a reference operation angle at the time of releasing the matching mode, the control valve 4 is controlled for open and close operation on the basis of the saved drive current, thereby starting the operation of the lift cylinder 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for cargo handling in industrial vehicles such as forklifts.

[0002]

2. Description of the Related Art Conventionally, for example, when a fork of a forklift is moved up and down, it is carried out based on the operating direction of a lift lever 51 as shown in FIGS. Operation amount) θ. That is, the electromagnetic proportional control valve 52 is switched based on the operation direction of the lift lever 51, and the fork 54 is moved up and down by the hydraulic oil supplied to or discharged from the lift cylinder 53. Further, the supply of the hydraulic oil of the electromagnetic proportional control valve 52 is adjusted based on the operation angle (operation amount) θ of the lift lever 51 to control the ascending / descending speed of the fork 54.

The lift control of the fork 54 will be described in detail. The lever operation angle θ of the lift lever 51 is detected by a lever operation detection sensor 55 including a potentiometer, and this detection signal is output to the controller 56.

The controller 56 is composed of an A / D converter 57, a CPU 58, a ROM 59, a RAM 60, a D / A converter 61 and a constant current amplifier 62. The detection signal from the lever operation detection sensor 55 is converted into a digital value by the A / D converter 57 and output to the CPU 58, and the CPU 58 calculates the operation angle θ of the lift lever 51 at that time.

When the CPU 58 calculates the lever operation angle θ, it calculates a drive current value I for energizing the electromagnetic proportional control valve 52 with respect to the operation angle θ based on a map shown in FIG. The drive current value I with respect to the operation angle θ shown in FIG. 12 is obtained in advance by testing or logically, and the ROM 59 is used as data.
I remember it.

The CPU 58 outputs a drive control signal for the drive current value I to the D / A converter 61 in order to drive and control the electromagnetic proportional control valve 52 with the drive current value I, and the D / A converter 61 drives the drive control signal. The control signal is converted into analog, and the drive current value I is supplied from the constant current amplifier 62 to the electromagnetic proportional control valve 52. Electromagnetic proportional control valve 5
2 supplies the lift cylinder 53 with hydraulic oil determined by the drive current value I (that is, the lever operation angle θ). Therefore, the drive current value I is obtained from the lever operation angle θ, and the drive current value I determines the supply of hydraulic oil at that time and determines the rising speed. That is, the ascending speed of the fork 54 is determined by the operation angle θ of the lift lever 51.

[0007]

However, when the opening ratios of the electromagnetic proportional control valves 52 of the same standard are individually controlled by the drive current value I, the flow rate characteristics of the hydraulic oil from the electromagnetic proportional control valves 52 do not always match. That is, FIG.
As shown in FIG. 1, since the electromagnetic proportional control valve 52 also has individual differences, the electromagnetic proportional control valve 52 A has a drive current value I1.
From the above, the hydraulic oil starts to be supplied to the open lift cylinder 52, and the electromagnetic proportional control valve 52 of B starts to supply the hydraulic oil to the open lift cylinder 52 from the drive current value I2 or more.

Therefore, the A proportional solenoid control valve 52
In the case of, the drive current value I for starting the lift of the lift cylinder 53 is I1, so when the operating angle θ of the lift lever 51 is set to θ1 as shown in FIG. The lift cylinder 53 starts rising.

On the other hand, in the case of the electromagnetic proportional control valve 52 of B, the drive current value I for starting the lift of the lift cylinder 53 is I2, so that the operating angle of the lift lever 51 as shown in FIG. When θ is set to θ2, the lift cylinder 52 starts to move up by the electromagnetic proportional control valve 52.

As a result, in the electromagnetic proportional control valve 52 of A, the lift lever 5 is operated from the neutral position to the operation angle θ1.
This is a dead zone in which the lift cylinder 53 does not operate even if 1 is operated. On the other hand, in the B electromagnetic proportional control valve 52, the lift cylinder 5 is operated from the neutral position to the operation angle θ2.
3 is a dead zone where it does not work.

Therefore, the width of the dead zone of the B control valve 52 is larger than that of the A proportional solenoid control valve 52, and the operability of the lift lever 51 is deteriorated. As a countermeasure against this, after assembling the forklift, the drive current value I output from the controller 56 to the electromagnetic proportional control valve 52 is adjusted so that when the lift lever 51 reaches a predetermined operation angle θ1 or more, the electromagnetic proportional It is possible to start the operation without being affected by the individual difference of each control valve 52, but there is a problem that it is very troublesome and time-consuming.

The present invention has been made to solve the above-mentioned problems, and its purpose is to start the operation of the cargo handling hydraulic equipment regardless of the individual difference of the control valve when the operation means is operated by the reference operation amount. An object of the present invention is to provide a cargo handling hydraulic control device for an industrial vehicle that can be easily adjusted.

[0013]

In order to solve the above problems, the present invention provides a control valve for adjusting the flow rate of hydraulic oil based on the operation amount when the operation device has a reference operation amount or more, and an operating speed. In the hydraulic control device for cargo handling in an industrial vehicle having a neutral dead zone for adjusting the operation of the hydraulic equipment for cargo handling to start the operation amount detecting means for detecting the operation amount of the operating means, and the detection by the operation amount detecting means. An opening control means for outputting a command signal to the control valve based on a signal to perform opening control, a matching mode setting means for setting a matching mode for adjusting an operation start point of the cargo handling hydraulic device, In the matching mode setting state, when the operation means has a predetermined adjustment operation amount, the opening control means changes to the control valve. Output control means for outputting a command signal that increases in a proportional manner, and a command signal that proportionally increases from the opening control means when the operating means is set to a predetermined adjustment operation amount in the matching mode setting state. Detecting means for detecting a command signal when the cargo handling hydraulic equipment starts operating based on hydraulic oil whose flow rate is adjusted by a control valve whose opening is controlled, and the command signal detected by the detecting means Storage means for storing as a command value and, in the matching mode release state, when the operation means reaches a reference operation amount, via the opening control means based on the opening command value stored in the storage means. The gist of the present invention is to include a cargo handling hydraulic control means for controlling the opening of the control valve and starting the operation of the cargo handling hydraulic equipment.

[0014]

In the state where the matching mode is set by the matching mode setting means for adjusting the operation start point of the hydraulic equipment for cargo handling, the operating means is set to a predetermined setting operation amount, and based on the control of the output control means. The opening control means outputs a command signal that increases proportionally to the control valve, and the control valve controls the opening based on the command signal. Then, when the detecting means detects the command signal when the operation of the cargo handling hydraulic equipment is started by the hydraulic fluid whose flow rate is adjusted by the control of the opening degree of the control valve, the storing means outputs the command signal to the opening degree command value. Memorize as.

In the state where the matching mode is released by the matching mode setting means, when the operating means is operated by the reference operation amount, the cargo handling hydraulic control means opens based on the opening command value stored in the storage means. A command signal is output to the control valve via the frequency control means. Then, the opening degree of the control valve is controlled by the cargo handling hydraulic control means, and the cargo handling hydraulic device starts operating.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the matching adjustment of a control valve for controlling a lift cylinder of a forklift according to the present invention will be described below with reference to FIGS.
Since the matching adjustment for the fork raising control and the matching adjustment for the lowering control are the same procedure, only the matching adjustment for the fork raising control will be described.

As shown in FIG. 1, the forklift is provided with a lift lever 1 as an operating means in its driver's seat. Then, the operation direction and the operation angle (operation amount) θ of the lift lever 1 are detected by a lever operation amount detection sensor (for example, a potentiometer) 2 as an operation amount detection means and output to the controller 3.

The controller 3 controls the opening of the control valve 4 to adjust the flow rate of hydraulic oil.
The adjusted hydraulic oil is supplied to the lift cylinder 5, and the lift cylinder 5 is controlled to be lifted. The lift speed of the fork 6 is controlled by the lift control of the lift cylinder 5.

That is, the controller 3 controls the lifting of the lift cylinder 5 and the fork 6 based on the operating direction and the operating angle θ of the lift lever 1. When the operation angle θ of the lift lever 1 is equal to or smaller than the preset reference operation angle θ1, a dead zone is provided to prevent the lift cylinder 5 from operating, and when the operation angle θ of the lift lever 1 is equal to or larger than the reference operation angle θ1, The opening of the control valve 4 is controlled by the controller 3 based on the operation angle θ, and the lift cylinder 5 and the fork 6 are controlled to be lifted.

Further, the lift lever 1 has a predetermined operation angle θn.
In the above case, the controller 3 controls the control valve 4 to a constant opening regardless of the operation angle θ, supplies the maximum amount of hydraulic oil to the lift cylinder 5, and raises the lift cylinder 5 at the maximum speed. It is like this.

The controller 3 uses the A / D converter 7 for converting the input detection signal into a digital signal, the RAM 8 for temporarily storing the calculation result, the ROM 9 for storing the work program and various data, and the lift lever 1 as a reference. When the operation angle is θ1, the drive current value (opening command value) I for starting the rise of the lift cylinder 5 and the EEPROM 10 as a storage means for storing a map (for speed control of the lift cylinder) described later, the input signal, and the RAM.
8, output control means for performing arithmetic processing based on various data of the ROM 9 and the EEPROM 10 and the work program,
CPU11 as a detection means and a cargo control hydraulic control means,
It comprises a D / A converter 12 for converting a command signal from the CPU 11 into an analog signal and a constant current amplifier 13 as an opening control means for outputting an output signal to the control valve 4 based on the command signal.

The A / D converter 7 is adapted to convert the detection signal from the lever operation amount detection sensor 2 into a digital signal and output it to the CPU 11. In addition, the A / D converter 7 converts the detection signal of the rotation speed sensor 14 serving as the rotation speed detecting means into a digital signal and outputs CP.
It is output to U11. The rotation speed sensor 14 detects the rotation speed of an engine 16 which operates a hydraulic pump 15 for supplying hydraulic oil to the lift cylinder 5.

A setting switch 17 as a matching mode setting means is connected to the CPU 11. Based on the ON operation of the setting switch 17, when the lift lever 1 is set to the reference operation angle θ1, the CPU 11 uses the hydraulic oil from the control valve 4 to lift the lift cylinder 5.
Is set to a matching adjustment mode in which matching adjustment is performed to start the rise.

As shown in FIG. 3, the ROM 9 stores a map for controlling the opening of the control valve 4. In this map, the drive current value I increases proportionally with the passage of time. The inclination of this map and the level of the drive current value I are based on the data obtained by experimentally controlling the opening of the control valve 4.

When the matching adjustment mode is set by the setting switch 17, the operating angle θ of the lift lever 1 is maximum, and the engine speed of the engine 16 reaches the maximum speed, the CPU 11 is stored in the ROM 9. The duty ratio is calculated based on the drive current value I in the map shown in FIG. 3, and the duty ratio is output to the constant current amplifier 13 via the D / A converter 12.
The constant current amplifier 13 outputs a drive current based on the duty ratio to the control valve 4 to energize the electromagnetic proportional solenoids 4a and 4b.

The electromagnetic proportional solenoids 4a, 4b of the control valve 4 are controlled valves 29a, 2 which will be described later according to the average drive current of the duty-controlled drive currents.
The opening of 9b is controlled. Therefore, since the drive current output from the constant current amplifier 13 increases proportionally with the passage of time, the opening amounts of the control valves 29a and 29b gradually increase, and eventually the control valve 4 is released.
The hydraulic oil is supplied to the lift cylinder 5 from the lift cylinder 5, and the lift cylinder 5 starts its operation.

When the CPU 11 detects that the operator has returned the lift lever 1 to the neutral position at the moment when the lift cylinder 5 starts to rise due to the hydraulic oil from the control valve 4 at time t1, the drive at that time is detected. The current value I1 is stored in the EEPROM 10.

Therefore, when the matching adjustment mode is released by the setting switch 17 and the lift lever 1 reaches the reference operation angle θ1, the CPU 11 causes the E
The drive current value I1 is read from the EPROM 10. The CPU 11 calculates the duty ratio based on the drive current value I1 and outputs it to the constant current amplifier 13 via the D / A converter 12. The constant current amplifier 13 outputs a drive current based on the duty ratio to the control valve 4. The electromagnetic proportional solenoids 4a, 4b of the control valve 4 are used to control the control valves 29a, 2
The opening degree of 9b is controlled, hydraulic oil is supplied from the control valve 4 to the lift cylinder 5, and the lift cylinder 5 starts an ascending operation.

Further, the lift lever 1 has a reference operation angle θ1.
When operated between .about..theta.n, the drive current value I is set based on the operation angle .theta., And the drive current value I is set by the map shown in FIG. In this map, when the lift lever 1 is equal to or smaller than the reference operation angle θ1, it is a dead zone in which the lift cylinder 5 is not operated, so the drive current value I is set to 0. Further, when the lift lever 1 is at a predetermined operation angle θn or more, the control valve 4 is irrespective of the operation angle θ at that time.
Is set to a drive current value I3 that maximizes the amount of opening of the lift cylinder 5 and supplies the hydraulic oil to the lift cylinder 5.

Then, when the drive current value I1 is set, the CPU 11 causes the drive current value I1, the coordinates (x1, y1) based on the reference operation angle θ1, and the drive current value I3,
A map is created by connecting the coordinates (x3, y3) based on the predetermined operation angle θn with a solid line, and the map is created using the EEPR.
It is designed to be stored in the OM10. Therefore, when the lift lever 1 reaches the reference operation angle θ1 after the matching adjustment mode is released by the setting switch 17, C
The PU 11 reads the drive current value I1 from the EEPROM 10.

Based on this drive current value I1, the CPU 11
Calculates the duty ratio and outputs it to the constant current amplifier 13 via the D / A converter 12. The constant current amplifier 13 outputs a drive current based on the duty ratio to the control valve 4. Therefore, the hydraulic oil from the control valve 4 is supplied to the lift cylinder 5, and the lift cylinder 5 starts operating.

Similarly, in the state where the matching adjustment mode of the setting switch 17 is set, the operating angle θ of the lift lever 1 is maximum, and the engine speed becomes the maximum speed, for example, at the time t2, from the control valve 4 When the CPU 11 detects that the operator has returned the lift lever 1 to the neutral position at the moment when the lift cylinder 5 starts to move up by the hydraulic oil, the drive current value I2 at that time is stored in the EEPROM 10.

Therefore, when the matching adjustment mode is released by the setting switch 17 and the lift lever 1 is operated, when the lift lever 1 reaches the reference operation angle θ1, the CPU 11 sets the drive current value I2 from the EEPROM 10. read out. CPU based on this drive current value I2
11 calculates the duty ratio and outputs it to the constant current amplifier 13 via the D / A converter 12. Constant current amplifier 13
Outputs a drive current based on the duty ratio to the control valve 4. Therefore, the hydraulic oil from the control valve 4 is supplied to the lift cylinder 5, and the lift cylinder 5 starts operating.

Similarly, in the map, when the drive current value I2 is set, the CPU 11 coordinates (x1, y2) based on the drive current value I2 and the reference operation angle θ1.
The drive current value I3 and the coordinates (x3, y3) based on the predetermined operation angle θn are connected by the chain double-dashed line shown in FIG. 4 to create a map, and the map is stored in the EEPROM 10. There is.

Therefore, only when the lift lever 1 is operated to the reference operation angles θ1 to θn after the matching adjustment mode is released by the setting switch 17, the CPU 11 operates based on the map shown by the chain double-dashed line in FIG. The drive current value I is read out, and the duty ratio based on the read drive current value I is calculated. If the lift lever 1 has an operation angle θ other than the reference operation angles θ1 to θn, the CPU 11 reads the drive current value I based on the map shown by the solid line in FIG.

Therefore, when the lift lever 1 is operated at the reference operation angle θ1 based on the individual difference of the control valve 4, the CPU 11 sets the drive current value I for starting the lift of the lift cylinder 5 and the set drive current. Based on the value I, the lift lever 1 moves the reference operation angles θ1 to θn.
The CPU 11 creates a map when

Next, the hydraulic circuit of the control valve 4 will be described in detail. As shown in FIG. 2, hydraulic oil supplied from the oil pump 15 is supplied to the control valve 4 by a supply pipe 21 and a diversion valve 22 via a main pipe 23 on the control valve 4 side. or,
The diversion valve 22 is provided with a PS pipe line 25 for power steering via a check valve 24.

A spool 26 is arranged in the control valve 4 and oil chambers 27 for pilot operation are formed at both ends thereof. This oil chamber 2
7, the spool 26 is slidable.
A spring 28 is provided in the oil chamber 27, and the spring 28 always holds the spool 26 in the neutral position.

In the oil chamber 27, a control valve 29a controlled to be opened and closed by the electromagnetic proportional solenoids 4a and 4b,
29b is connected. Therefore, the constant current amplifier 1
A drive current having a duty ratio based on the drive current value I output from the motor 3 is supplied to the electromagnetic solenoids 4a and 4b, and the control valves 29a and 29b are controlled to open / close with an average drive current based on the duty ratio. The control valves 29a, 29
The flow rate of the hydraulic oil supplied to the control valves 29a and 29b is adjusted by the opening / closing control of b to be supplied to the oil chamber 27.

A pilot drain pipe 30 is connected to each of the oil chambers 27 and is led out to a tank or a return pipe line. The pilot drain pipes 30 flow out from the oil chambers 27. A throttle valve (orifice) 31 that regulates the outflow amount of hydraulic oil is provided.

That is, the control valve 4 controls the opening and closing of the control valves 29a and 29b based on the energization of the electromagnetic proportional solenoids 4a and 4b for raising or lowering, and the working oil is introduced into the oil chamber 27 while the inside of the oil chamber 27 is controlled. Of the working oil is discharged at a flow rate limited by the throttle valve 31 of the pilot drain pipe 30 to control the magnitude of the working oil pressure acting on the spool 26.
The spool 26 is displaced to a position in which the forces of are balanced.

Therefore, by controlling the opening of the control valves 29a and 29b based on the average drive current of the duty-controlled drive currents supplied to the electromagnetic proportional solenoids 4a and 4b, the corresponding position of the spool 26 can be changed. As a result, the lift cylinder 5 is supplied or discharged with an amount of hydraulic oil corresponding to the position of the spool 26. That is, the lift cylinder 5 is adapted to move up at a speed corresponding to the position of the spool 26.

Next, the operation of the cargo handling hydraulic control device configured as described above will be described with reference to the flowcharts shown in FIGS. In step 1, when the ignition switch is operated, the RAM of the controller 3
8. The EEPROM 10 is initialized. Then, in step 2, the CPU 11 causes the setting switch 17
It is determined whether or not it is the matching adjustment mode by the ON operation of. When the matching adjustment mode is set by the setting switch 17, the CPU 11 determines whether or not the lift lever 1 for raising the lift cylinder 5 is operated in step 3 based on the detection signal of the lever operation amount detection sensor 2. ..

When the lift lever 1 for operating the tilt cylinder and the reach cylinder is operated, the CPU 11
Is determined, the processing for performing these matching adjustments is performed in step 4.

When the CPU 11 determines in step 3 that the operator adjusts the lift cylinder 5 by the operation of the lift lever 1, the CPU 11 determines in step 5 based on the detection signal of the lever operation amount detection sensor 2 that the operator operates. It is determined whether or not the lift lever 1 has reached the maximum operation angle θ by the operation.

When the CPU 11 determines based on the detection signal of the lever operation amount detection sensor 2 that the lift lever 1 has reached the maximum operation angle θ by the operation of the operator, the CPU 11 determines that the rotation speed sensor 14 is operating in step 6. Based on the detection signal, it is determined whether or not the engine speed of the engine 16 has become the maximum by the operation of the operator.

When the CPU 11 determines in step 7 that the engine speed has reached the maximum based on the detection signal of the rotation speed sensor 14, the CPU 11 responds to the passage of time in the map shown in FIG. Then, the duty ratio based on the increasing drive current value I is calculated,
The duty ratio is output to the constant current amplifier 13 via the D / A converter 12.

The constant current amplifier 13 outputs a drive current based on the duty ratio to the control valve 4 to energize the electromagnetic proportional solenoids 4a and 4b. The electromagnetic proportional solenoids 4a and 4b of the control valve 4 are controlled in their opening degree by the average drive current of duty-controlled drive currents.

At step 8, since the drive current output from the constant current amplifier 13 increases proportionally with the passage of time, the opening amounts of the control valves 29a and 29b become large, and for example, at the time t1, from the control valve 4 is increased. The CPU 11 determines whether or not the operator has returned the lift lever 1 to the neutral position at the moment when the lift cylinder 5 starts to be lifted by the hydraulic oil.

In step 9, when the CPU 11 determines that the operator has returned the lift lever 1 to the neutral position based on the detection signal from the lever operation amount detection sensor 2, the CPU 11 of FIG.
The drive current value I1 at that time is calculated based on the map of
It is stored in the EPROM 10. Further, at the time when the drive current value I1 is set, as shown in FIG. 4, the CPU 11 sets the coordinates (x1, y) based on the drive current value I1 and the reference operation angle θ1.
1) and the drive current value I3 and the coordinates (x3, y3) based on the predetermined operation angle θn are connected by a solid line to create a map, and this map is stored in the EEPROM 10. As a result, the matching adjustment of the lift cylinder 5 is completed, and the process proceeds to step 2 again.

After the matching adjustment is completed, in step 2, the CPU 11 determines whether or not the matching adjustment mode is released by the setting switch 17,
When the CPU 11 determines that the matching mode is released, the CPU 11 determines the lift lever 1 based on the detection signal of the lever operation amount detection sensor 2 in step 10.
The operation angle θ of is detected.

That is, when the CPU 11 determines that the operation angle θ of the lift lever 1 is less than or equal to the reference operation angle θ1 from the neutral position, the CPU 11 drives the drive current based on the map shown by the solid line in FIG. Read the value I. In this case, the drive current value I is 0 because it is a dead zone for preventing the lift cylinder 5 from rising, and the CPU 11 causes the constant current amplifier 13 via the D / A converter 12 to perform the duty based on the drive current value I. Do not output the ratio. As a result, the lift cylinder 5 does not start rising.

In step 11, the CPU 11 determines that the operation angle θ of the lift lever 1 is the reference operation angle θ1.
When the determination is made, the CPU 11 reads out the drive current value I1 corresponding to the reference operation angle θ1 of the lift lever 1 based on the map shown by the solid line in FIG. 4 stored in the EEPROM 10. The CPU 11 calculates the duty ratio based on the read drive current value I1 and calculates the duty ratio as D / A.
It outputs to the constant current amplifier 13 via the converter 12.

Thereafter, in step 12, the constant current amplifier 13 outputs a drive current based on the duty ratio to the electromagnetic proportional solenoids 4a and 4b of the control valve 4. Then, the opening of the control valves 29a and 29b is controlled by the average drive current of the duty-controlled drive currents. Therefore, the flow rate of the hydraulic oil supplied from the control valve 4 is adjusted, and the lift cylinder 5 starts rising. After that, the process proceeds to step 2 again, and the same processing as above is performed.

Further, in step 11, if the operation angle θ of the lift lever 1 is within the range of the reference operation angles θ1 to θn, the CPU 1 is detected based on the detection signal of the lever operation amount detection sensor 2.
When 1 determines, the CPU 11 reads the drive current value I corresponding to the operation angle θ of the lift lever 1 based on the map shown by the solid line in FIG. 4 stored in the EEPROM 10. The CPU 11 calculates a duty ratio based on the drive current value I, and this duty ratio is output to the constant current amplifier 13 via the D / A converter 12.

In step 12, the constant current amplifier 13
Outputs a drive current based on the duty ratio to the electromagnetic proportional solenoids 4a and 4b of the control valve 4. Then, the opening of the control valves 29a and 29b is controlled by the average drive current of the duty-controlled drive currents. Therefore, the rising speeds of the lift cylinder 5 and the fork 6 are set based on the drive current value I based on the operation angle θ of the lift lever 1. After that, the process proceeds to step 2 again, and the same processing as above is performed.

Further, in step 11, the CPU 11 determines that the operation angle θ of the lift lever 1 is equal to or larger than the predetermined operation angle θn based on the detection signal of the lever operation amount detection sensor 2.
When the PU 11 judges, the CPU 11 judges that the EEPROM 1
Based on the map shown by the solid line in FIG. 4 stored in 0, the drive current value I3 is read out regardless of the operation angle θ of the lift lever 1. The CPU 11 calculates the duty ratio based on the drive current I3, and this duty ratio is output to the constant current amplifier 13 via the D / A converter 12.

In step 12, the constant current amplifier 13
Outputs a drive current based on the duty ratio to the electromagnetic proportional solenoids 4a and 4b of the control valve 4. Then, the opening of the control valves 29a and 29b is controlled by the average drive current of the duty-controlled drive currents. Therefore, the rising speeds of the lift cylinder 5 and the fork 6 are set based on the drive current value I based on the operation angle θ of the lift lever 1. At this time, since the opening amount of the control valve 4 is maximized, the lift speed of the lift cylinder 5 is set to the maximum and the lift is increased. After that, the process proceeds to step 2 again, and the same processing as above is performed.

Even when the drive current value I becomes I2, the map shown by the chain double-dashed line in FIG. 4 is created by the same procedure as above, and the opening control of the control valve 4 is performed based on the map. Be seen.

Therefore, if the operating angle θ of the lift lever 1 is set to the reference operating angle θ1 after the matching adjustment of the control valve 4 is performed by the setting switch 17, the controller 3 always controls the opening of the control valve 4 and lifts the lift. The cylinder 5 can always start rising.

Therefore, it is possible to start the lift of the lift cylinder 5 when the lift lever 1 is set to the reference operation angle θ1 without affecting the individual difference of the control valve 4.
As a result, the width of the dead zone can be made constant and the operability of the lift lever 1 can be improved.

Further, since the width of the dead zone can be made constant, the speed control range of the lift cylinder 5 and the fork 6 is widened, and it is easy to match the speed of the lift cylinder 5 and the fork 6 with any speed.

In the present embodiment, the lift control for raising the lift cylinder 5 of the forklift is applied, but the map as shown in FIG. 7 is stored in the EEPROM 10 based on the map creation after the matching adjustment similar to the above. For example, when the lift lever 1 is set to the reference operation angle −θ1, the lowering of the lift cylinder 5 can be surely started without affecting the individual difference of the control valve 4.

As another example of this embodiment, as shown in FIG. 1, the CPU 11 of the controller 3 may be provided with a lamp 34 indicating that the matching adjustment mode is set. The lamp 34 is turned on when the matching adjustment mode is set by the setting switch 17, and the lamp 34 is turned off when the matching adjustment of the control valve 4 is completed. As a result, whether or not the matching adjustment mode is set can be easily determined by lighting the lamp 34.

In the present embodiment, the procedure for creating the map of FIG. 4 has been described based on the characteristic diagram of the control valve 4 showing the flow rate of the hydraulic oil with respect to the drive current value I of FIG.
That is, the characteristics of the control valve 4 in FIG. 12 are that the drive current values I at which the flow rate of the hydraulic oil becomes the maximum match.

However, it may be considered that the characteristics of the control valve 4 as shown in FIG. 8 can be obtained. That is, the characteristics of the control valve 4 shown in FIG. The procedure for creating a map in this case is performed as follows.

In the valve having the flow rate characteristic of the hydraulic oil with respect to the drive current value I shown by the solid line in FIG. 8, first, the drive current value I5 at which the supply of the hydraulic oil is started is obtained, and then the maximum flow rate of the hydraulic oil is reached. The drive current value I6 is obtained. Then, as indicated by the solid line in FIG. 9, the reference operation angle θ1 and the drive current value I5
The coordinates (x1, y5) with respect to and the coordinates (x2, y4) with respect to a predetermined operation angle θn and drive current value I6 are connected by a solid line to create a map. This map is EEPROM1
0, and then the drive current value I corresponding to the operation angle θ of the lift lever 1 is read out based on the map stored in the EEPROM 10.

Next, in the valve of the flow rate characteristic of the hydraulic oil with respect to the drive current value I shown by the chain double-dashed line in FIG. 8, first, the drive current value I7 at which the supply of the hydraulic oil is started is obtained, and then the hydraulic oil is The drive current value I8 that gives the maximum flow rate is obtained. Then, as indicated by the chain double-dashed line in FIG. 9, the reference operation angle θ1,
The coordinates (x1, y7) with respect to the drive current value I7, the predetermined operation angle θn, and the coordinates (x2, y with respect to the drive current value I8.
Create a map by connecting 6) with the two-dot chain line. This map is stored in the EEPROM 10, and the drive current value I with respect to the operation angle θ of the lift lever 1 is then stored in the EEPROM.
Read based on the map stored in 10.

The map shown by the chain double-dashed line shifts in parallel to the map shown by the solid line in FIG. 9 and the drive current value I becomes higher as a whole, so that the flow rate of hydraulic oil seems to increase. .. However, as shown in FIG. 9, for example, the drive current value I when the operation angle θ of the lift lever 1 is θp is set to IA and IB based on the respective maps. The flow rate of the hydraulic oil is constant when the drive current values IA and IB are associated with the map shown in FIG. Therefore, the operating speed of the lift cylinder 5 with respect to the operation angle θ of the lift lever 1 can be made constant regardless of the influence of the individual difference of the control valve 4.

In the present embodiment, the matching adjustment when the lift cylinder 5 is lifted has been described, but this cargo handling hydraulic control device can also be applied to a tilt cylinder and a reach cylinder.

Further, in the present embodiment, when the operator sets the lift lever 1 to the maximum operation angle θ and the engine speed to the maximum speed during matching adjustment, the drive current value I shown in FIG. Although it is output to the control valve 4, it is not always necessary to maximize the operation angle θ of the lift lever 1 and set the engine rotation speed to the maximum rotation speed, and it is also possible to set it arbitrarily. Further, when the hydraulic pump 15 is always rotating at a constant rotation speed by driving other than the engine 16, when the lift lever 1 is set to the maximum operation angle θ, the controller 3 causes the drive current value based on FIG. It can also be configured to output I.

In this embodiment, when the lift cylinder 5 starts to operate, the operator lifts the lift lever 1
To the neutral position, and based on this, the controller 3 determines that the lift cylinder 5 has started its operation, and
The drive current value I, which is the starting point of the lift cylinder 5 at that time, is detected. In addition to this, a detection sensor for detecting the lift of the lift cylinder 5 is provided, and the lift cylinder 5 operates based on this sensor. It is also possible to configure so as to detect the drive current value I serving as the starting point based on the start.

Although this embodiment is embodied as a forklift, it can be applied to other industrial vehicles.

[0074]

As described in detail above, according to the present invention, even if the operating means is operated more than the reference amount, the cargo handling hydraulic equipment can be reliably operated even if the rotation speed of the drive source for supplying hydraulic oil changes. There is an excellent effect that can be operated.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a forklift cargo handling hydraulic control device embodying the present invention.

FIG. 2 is a hydraulic control circuit diagram of a control valve.

FIG. 3 is a characteristic diagram showing a map in which drive current values are set with the passage of time.

FIG. 4 is a characteristic diagram showing a map in which a drive current value is set for an operation angle.

FIG. 5 is a flowchart illustrating matching adjustment of a cargo handling hydraulic control device.

FIG. 6 is a flowchart illustrating matching adjustment of the cargo handling hydraulic control device.

FIG. 7: When the lift cylinder descends, the tilt cylinder,
It is a characteristic view showing a map for setting a drive current value corresponding to an operation angle when applied to a reach cylinder.

FIG. 8 is a characteristic diagram showing another example in which characteristics of individual differences of control valves are different.

9 is a characteristic diagram showing a map in which a drive current value with respect to an operating angle is set based on the characteristic of FIG.

FIG. 10 is a block circuit diagram of a conventional cargo handling hydraulic control device for a forklift.

FIG. 11 is a characteristic diagram showing individual differences of electromagnetic proportional control valves.

FIG. 12: Due to the influence of individual differences of the electromagnetic proportional control valve,
FIG. 6 is a characteristic diagram showing that the drive current value changes and the dead zone width changes.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lift lever as operation means, 2 ... Lever operation amount detection sensor as operation amount detection means, 3 ... Controller as output control means and cargo handling hydraulic control means, 4 ... Control valve, 5 ... Cargo handling hydraulic equipment Lift cylinder, 10 ... EEPROM as storage means, 13
... constant current amplifier as opening / closing control means, 17 ... setting switch as matching mode setting means, θ ... operation angle as operation amount, θ1 ... reference operation angle as reference operation amount

Claims (1)

[Claims] 1. When the operation means is set to a reference operation amount or more,
In the cargo handling hydraulic control device for an industrial vehicle having a neutral dead zone for adjusting the flow rate of the hydraulic oil by the control valve based on the operation amount and adjusting the operating speed to start the operation of the cargo handling hydraulic device, An operation amount detecting means for detecting an operation amount of, an opening control means for outputting an instruction signal to the control valve to perform an opening control based on a detection signal by the operation amount detecting means, and the cargo handling hydraulic equipment. A matching mode setting means for setting a matching mode for adjusting the operation start point of the, and in the matching mode setting state, when the operating means has a predetermined adjustment operation amount, from the opening control means to the control valve Output control means for outputting a command signal that increases in proportion, and the operation in the matching mode setting state. The hydraulic equipment for cargo handling based on hydraulic oil whose flow rate is adjusted by a control valve whose opening is controlled by a command signal proportionally increased from the opening control means when the means is set to a predetermined adjustment operation amount. Detecting means for detecting the command signal when the operation is started, storage means for storing the command signal detected by the detecting means as an opening command value, and in the state where the matching mode is released, the operation means is a reference operation amount. Hydraulic pressure for cargo handling, which controls the opening degree of the control valve through the opening degree control means based on the opening degree command value stored in the storage means to start the operation of the hydraulic equipment for cargo handling. A hydraulic control device for cargo handling in an industrial vehicle, comprising: