JPH10291796A - Setting method for current value for controlling backward tilting speed of mast of indusrial vehicle and control device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply set a current value for controlling backward tilting speed of a mast by gradually raising a command current value to a solenoid valve under the condition in which a hydraulic pump is driven at fixed rotating speed and a tilt cylinder is operated to backward tilt, and setting the command current value when the backward tilting speed of the mast becomes a fixed value to be the current value for limiting backward tilting speed. SOLUTION: A CPU 53 inputs the output signals of a lift height sensor 14, a potentiometer 15, a pressure sensor 17, a forward tilting detecting switch 18, and a backward tilting detecting switch 19, and at operating a tilt cylinder 9, a control command signal to a proportional solenoid valve 43 is output through a solenoid drive circuit 52. When a matching switch 59 is in a state of ON and the backward tilting detecting switch 19 becomes ON, the CPU 53 outputs the command current value to the proportional solenoid valve 43 so as to gradually raise it, and sets the command current value when the backward tilting speed of a mast 3 based on the detected signal of the potentiometer 15 becomes a fixed value to be the current value for limiting the backward tilting speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mast for an industrial vehicle in which a mast for raising and lowering an attachment for cargo handling is tiltably provided, and a flow rate of hydraulic oil supplied to a tilt cylinder for tilting the mast is controlled by a solenoid valve. The present invention relates to a method and a control device for setting a current value for controlling the backward tilt speed.

[0002]

2. Description of the Related Art In a forklift, which is an industrial vehicle of this kind, a fork is raised and lowered together with a lift bracket by a mast provided with an outer mast and an inner mast provided at a front portion of the vehicle. The mast is expanded and contracted by the operation of the lift cylinder based on the operation of the lift lever, and the fork is raised and lowered accordingly. Further, in order to facilitate the cargo handling operation and to improve the stability during traveling of the forklift, the mast is tilted forward or backward with respect to the vertical reference position by operating the tilt cylinder based on the operation of the tilt lever. .

[0003] In a forklift, when a load is loaded on a fork, the center of gravity moves forward, and when the forklift height is increased, the moment acting on the mast increases. When the mast is tilted forward with a load being loaded, the center of gravity moves forward, and the stability of the forklift in the front-rear direction deteriorates. In addition, if the rearward inclination angle is too large in a state where the load is large, the center of gravity may be too close to the rear side, and the front wheels may be slightly lifted and slippage may occur. Therefore, conventionally, the forward tilt angle and the backward tilt angle of the mast have been set to predetermined values.

[0004] Conventionally, when the mast is tilted forward, the tilting speed becomes slower than during the backward tilting operation in order to prevent the collapse of the load and the lifting of the rear wheels of the forklift (ie, an unstable state in the longitudinal direction of the vehicle). As described above, the flow path is provided with a restriction to restrict the flow rate of the hydraulic oil. In addition, the worker also carefully leans forward at a low speed by performing inching operation so that the mast does not lean forward too much when the load is placed at a high place in the cargo handling operation. However, during backward tilting operation, stability is relatively good even when the load is large and the lift is high,
No throttle was provided in the flow path.

[0005]

When the load is high and the load is high, the operator leans backward at a relatively slow speed by adjusting the operation amount of the tilt lever and the engine speed during the backward tilting operation. Was working. However, when the mast is stopped at the last inclined position at a high speed due to an erroneous operation or the like while the load is being loaded, the shock is large, and the durability is reduced. Also, even if no load is loaded, if the rearward tilting operation is performed at a high elevation and at high speed, the rear shock will be lifted by the start shock at the start of rearward tilt, and the mast will stop at the last tilt position. The shock at the time is large, and causes the durability to decrease.

In order to solve this problem, the applicant of the present invention controls the flow rate of hydraulic oil supplied to the tilt cylinder that tilts the mast by using a solenoid valve whose opening is adjusted by a command current from the control means. Invented a device for limiting the backward tilting speed of the mast by lifting. The solenoid valve is constituted by a spool valve, and the amount of movement of the spool, that is, the opening (flow rate) is adjusted in accordance with the exciting current supplied to the solenoid. The magnitude of the exciting current is set by a command current value from the control means. And
The control means stores in the storage means a command current value used when limiting the backward tilt speed, and outputs the command current value when the backward tilt speed is limited.

However, even if the solenoid valve has the same standard, the current-flow rate (opening) characteristic varies slightly depending on the product, so that the solenoid valve varies the flow rate, that is, the backward tilt speed, even with the same command current value. For example, as shown in FIG.
The flow rate varies in the range of L1 to L2 with respect to the command current value Is. If a high-precision solenoid valve is used, the variation can be reduced, but the structure becomes complicated and the manufacturing cost increases.

In order to make each forklift limit the backward leaning speed as specified by using a normal solenoid valve without using a high-precision electromagnetic valve, the mast is manufactured at a predetermined backward leaning limited speed after the forklift is manufactured. It is necessary to set a command current value for tilting backward. However, there is a problem that this setting work is troublesome.

A first object of the present invention is to provide an industrial vehicle in which the flow rate of hydraulic oil supplied to a tilt cylinder that tilts a mast is controlled by a solenoid valve. It is an object of the present invention to provide a method of setting a current value for controlling the backward tilt speed of a mast of an industrial vehicle, which can easily set the current value for controlling the backward tilt speed of a mast.
A second object is to provide a control device suitable for performing the setting method.

[0010]

In order to achieve the first object, according to the first aspect of the present invention, a mast for raising and lowering a cargo handling attachment is tiltably provided, and a tilt cylinder for tilting the mast is provided. A method for setting a current value for controlling the backward tilting speed of a mast of an industrial vehicle in which a supply flow rate of hydraulic oil is controlled by a solenoid valve whose opening is adjusted by a command current from a control means, In a state in which the tilt cylinder is driven at a rotation speed and the tilt cylinder is tilted rearward, a command current value to the solenoid valve is gradually increased, and detection from tilt angle detection means capable of continuously detecting a tilt angle of the mast is performed. The signal is monitored, and a command current value when the backward tilt speed reaches a predetermined value is set as a current value for limiting the backward tilt speed.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means increases the command current value by a constant amount at regular time intervals, during which the backward tilting speed is a predetermined value. Is set as the current value for limiting the backward tilting speed.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a current value to be set as the backward leaning speed limiting current value is obtained a plurality of times, and the average value thereof is backward leaned. Set as speed limiting current value.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the predetermined rotation speed of the hydraulic pump is a maximum rotation speed. In order to achieve the second object, in the invention according to claim 5, a mast for vertically moving the cargo handling attachment is tiltably provided, and a supply flow rate of hydraulic oil to a tilt cylinder for tilting the mast is controlled by an electromagnetic valve. In an industrial vehicle to be controlled, a mast angle detecting unit for detecting a tilt angle of the mast from a reference position, a switching unit for switching a control unit for controlling an opening of the solenoid valve between a normal mode and an adjustment mode, A rearward tilting operation detecting means for detecting whether the operating means has been operated to the rearwardly tilting position, and a command current value for controlling the opening of the solenoid valve in accordance with a predetermined condition, and the switching means Switch to adjustment mode,
And a control unit for outputting a command current value to the solenoid valve so as to gradually increase when a rearward tilt detection signal is output from the rearward tilt operation detection unit, and a detection of the mast angle detection unit in the adjustment mode. Setting means for calculating the backward tilt speed of the mast based on the signal, and setting the command current value when the value becomes a predetermined value as a current value for limiting the backward tilt speed.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, in the adjustment mode, the control means increases the command current value by a constant amount at regular time intervals. According to the invention described in claim 7, in an industrial vehicle, a mast for raising and lowering the loading / unloading attachment is tiltably provided, and a supply flow rate of hydraulic oil to a tilt cylinder for tilting the mast is controlled by a solenoid valve. Mast angle detecting means for detecting the tilt angle from the reference position of the above, switching means for switching the control means for controlling the opening of the solenoid valve between the normal mode and the adjustment mode, and the tilt operating means operating to the backward tilt position A tilting operation detecting means for detecting whether or not the tilt cylinder has been switched to an adjustment mode, and when a tilting detection signal is output from the tilting operation detecting means, the tilt cylinder is normally tilted rearward. Control means for operating at a speed lower than the speed and gradually increasing the speed.

Therefore, according to the first aspect of the present invention, the supply flow rate of the hydraulic oil to the tilt cylinder is controlled by the solenoid valve whose opening is adjusted by the command current from the control means. When the current value for controlling the backward tilting speed of the mast is set, in a state where the hydraulic pump is driven at a predetermined rotational speed and the tilt cylinder is backwardly tilted,
The command current value to the solenoid valve is gradually increased, and the detection signal from the tilt angle detecting means is monitored.
Then, the command current value when the mast's rearward tilting speed reaches a predetermined value is set as a current value for limiting the rearward tilting speed.

According to a second aspect of the present invention, in the first aspect of the present invention, the command current value is changed so as to increase by a fixed amount at regular intervals. Then, the output of the tilt angle detecting means during that time is monitored, and the command current value when the rearward tilting speed of the mast reaches a predetermined value is set as a current value for restricting the rearward tilting speed.

According to a third aspect of the present invention, in the first or second aspect of the present invention, an operation for obtaining a current value to be set as the backward tilt speed limiting current value is performed a plurality of times. Then, the average value of the obtained current values for a plurality of times is set as the current value for limiting the backward inclination speed.

According to a fourth aspect of the present invention, in the first aspect of the present invention, when the hydraulic pump is driven at a maximum rotational speed, the current value for limiting the backward tilting speed is set. Is set.

According to the fifth aspect of the invention, the supply flow rate of the hydraulic oil to the tilt cylinder is controlled by the solenoid valve whose opening is adjusted by a command current from the control means. The tilt angle of the mast from the reference position is detected by the mast angle detecting means. The control means is switched between the normal mode and the adjustment mode by the switching means. The backward tilt operation detecting means detects whether the tilt operating means has been operated to the backward tilt position. A command current value for controlling the opening of the solenoid valve is output from the control means according to a predetermined condition. The switching means is switched to an adjustment mode,
When the rearward tilt detection signal is output from the rearward tilt operation detecting means, the command current value to the solenoid valve is gradually increased. Further, in the adjustment mode, the backward tilting speed of the mast is calculated by the setting unit based on the detection signal of the mast angle detecting unit, and the command current value when the value reaches a predetermined value is used for limiting the backward tilting speed. It is set as a current value.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, in the adjustment mode, the command current value to the solenoid valve is output so as to increase by a constant amount at regular time intervals.

According to the present invention, the supply flow rate of the hydraulic oil to the tilt cylinder is controlled by the solenoid valve whose opening is adjusted by a command current from the control means. The tilt angle of the mast from the reference position is detected by the mast angle detecting means. The control means is switched between the normal mode and the adjustment mode by the switching means. The backward tilt operation detecting means detects whether the tilt operating means has been operated to the backward tilt position. When the switching means is switched to the adjustment mode and the backward tilt detection signal is output from the backward tilt operation detecting means, the tilt cylinder is driven at a speed lower than the normal backward tilt speed and the speed is gradually increased. Is activated.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a forklift as an industrial vehicle to which a fork is attached as a cargo handling attachment will be described with reference to FIGS.

As shown in FIG. 4, a mast 3 is provided at the front of the body frame 2 of the forklift 1. The mast 3 includes a pair of left and right outer masts 3a that are supported to be tiltable with respect to the body frame 2, and inner masts 3b that are provided inside the masts 3 so as to be able to move up and down. A lift cylinder 4 is fixed to the rear side of both outer masts 3a in parallel with the outer mast 3a, and the tip of a piston rod 4a is connected to the upper part of the inner mast 3b. A lift bracket 5 is provided inside the inner mast 3b so as to be able to move up and down along the inner mast 3b, and a fork 6 is attached to the lift bracket 5. Innamasto 3
A chain wheel 7 is supported on an upper part of the lift cylinder 4, and a first end of the chain wheel 7 is provided on an upper part of the lift cylinder 4.
A chain 8 having a second end connected to the lift bracket 5 is mounted. And lift cylinder 4
The fork 6 is moved up and down together with the lift bracket 5 via the chain 8 by the expansion and contraction of the fork 6.

A base end of a tilt cylinder 9 is rotatably supported on both left and right sides of the body frame 2, and a distal end of a piston rod 9a is rotatably connected to an outer surface of the outer mast 3a. Then, the mast 3 is tilted by the expansion and contraction of the piston rod 9a of the tilt cylinder 9.

In the front part of the cab 10, a steering wheel 11,
A lift lever 12 as a lift operation means and a tilt lever 13 as a tilt operation means are provided, respectively. FIG. 4 shows the levers 12 and 13 in an overlapping state. The operation of the lift lever 12 causes the lift cylinder 4 to expand and contract, and the tilt lever 13
The tilt cylinder 9 is expanded and contracted by the operation described above.

As shown in FIG. 3, the outer mast 3a is provided with a lift sensor 14 as a lift detecting means at a predetermined height. The lift sensor 14 is composed of a proximity switch, and when a detected portion (not shown) fixed to the inner mast 3b is detected, the lift of the fork 6 is turned on when the lift is equal to or higher than the set value H0. It is turned off. The elevation sensor 14 outputs a predetermined voltage of a high level (H) in an on state, and outputs a predetermined voltage of a low level (L) in an off state. Further, in this embodiment, the set value H0 is almost half of the maximum lift Hmax.
Is set to a height of

The body frame 2 is provided with a rotary potentiometer 15 as mast angle detecting means. The potentiometer 15 is provided on a support portion rotatably supporting the base end of the tilt cylinder 9, and includes a rotary piece 15 a for holding a pin 16 protruding from the tilt cylinder 9. The turning piece 15a turns together with the tilt cylinder 9 in accordance with the expansion and contraction of the piston rod 9a, and the potentiometer 15 outputs a detection signal corresponding to the turning amount of the turning piece 15a. In this embodiment, the potentiometer 15 has the lowest output voltage when the mast 3 is located at the most inclined position and the largest output voltage when it is located at the most inclined position. Thus, the output voltage changes. Therefore,
The relationship between the tilt angle θ and the output voltage V of the potentiometer 15 decreases from the output value at the reference position if the mast 3 is tilted forward from the reference position where the mast 3 is vertical, as shown in FIG.
When tilted backward, the output value at the reference position is increased. That is, the potentiometer 15 outputs a voltage corresponding to the amount of tilt of the mast 3 from the reference position.

The lift cylinder 4 has a pressure sensor 17 as a load detecting means for detecting the load of the fork 6.
Is provided. The pressure sensor 17 is a lift cylinder 4
And outputs a detection signal corresponding to the load of the fork 6.

As shown in FIG. 5, in the vicinity of the tilt lever 13, a forward tilt detecting switch 1 as forward tilt operation detecting means is provided.
8 and a rearward tilt detection switch 19 as a rearward tilt operation detecting means
Are provided. Both detection switches 18 and 19 are micro switches, and the forward tilt detection switch 18 is turned on when the tilt lever 13 is in the forward tilt position, and is turned off when the tilt lever 13 is in any other position. Back tilt detection switch 19
Turns on when the tilt lever 13 is in the backward tilt position,
It is off when it is in any other position.

Next, a hydraulic circuit for driving the lift cylinder 4 and the tilt cylinder 9 will be described with reference to FIG. As shown in FIG. 6, the bottom chamber 4 of the lift cylinder 4
“b” is connected to a lift control valve 22 via a pipe line 20. A manually operated 7-port, 3-position switching valve is used for the lift control valve 22. The lift control valve 22 is a, b, c corresponding to the ascending, neutral, and descending operation positions of the lift lever 12 for instructing the fork 6 to move up and down. It is possible to switch between the three states. Tilt control valve 2 as manually operated direction switching valve
3 is provided with a 6-port, 3-position switching valve. The tilt lever 13 instructs the tilting and stopping of the fork 6 in three states of c, b, and a corresponding to the forward tilt, neutral, and rear tilt operating positions. It can be switched.

A hydraulic pump 25 for supplying hydraulic oil in an oil tank 24 to each of the cylinders 4 and 9 is driven by an engine E (shown in FIG. 4). The hydraulic pump 25 is connected to a port P1 of the lift control valve 22 via a hydraulic oil supply line 26 as a main line. Hydraulic oil supplied from the hydraulic pump 25 is supplied to the hydraulic oil supply line 26 with the cargo handling device side (lift cylinder 4 and tilt cylinder 9).
A flow divider 28 is provided for diverting to the power steering valve 27 side. Hydraulic oil supply line 26
Are ports P2 and P3 via branch pipes 26a and 26b branched downstream of the flow divider 28.
Connected to each other. A check valve 29 is provided in the branch conduit 26a. The hydraulic oil supply line 26 is connected to a return line 32 via a line 31 a provided with a relief valve 30. Lift control valve 22 is connected to return line 32 at port T1, to line 20 at port A1, to line 31b at port A2, and to port A3.
Are connected to the pipeline 34 respectively. Conduit 31
b is connected to the return line 32, and a relief valve 33 is provided on the way. The set pressure of the relief valve 33 is set to a value smaller than the set pressure of the relief valve 30.

The lift control valve 22 is disposed at the position a based on the lifting operation of the lift lever 12, and connects the branch line 26a and the line 20 at the position a to extend the lift cylinder 4. The lift control valve 22 is disposed at the position c based on the lowering operation of the lift lever 12, and branches the line 20 and the return line 32, the hydraulic oil supply line 26 and the line 34 at the position c. The pipe 26b and the pipe 31b are communicated with each other to contract the lift cylinder 4.

The lift control valve 22 is arranged at a position b based on the neutral operation of the lift lever 12, and connects the hydraulic oil supply line 26 and the line 34 with the branch line 26b at the position b. 31b. And
The communication between the pipe 20 and the branch pipe 26a and the return pipe 32 is interrupted, and the state in which the movement of the hydraulic oil in the lift cylinder 4 is prevented is maintained.

The hydraulic pump 25 is connected to a port P11 of the tilt control valve 23 via a hydraulic oil supply pipe 35 branched from the hydraulic oil supply pipe 26. A check valve 36 is provided in the hydraulic oil supply pipe 35. A pipe 34 is connected to a port P12 of the tilt control valve 23. The tilt control valve 23 is connected to the return line 32a at the port T11 and to the return line 32b at the port T12. Port A for tilt control valve 23
11 at line 37a and port A12 at line 37.
b. The pipe 37a is in the rod chamber 9b of the tilt cylinder 9, and the pipe 37b is in the bottom chamber 9c.
Connected to each other.

The tilt control valve 23 is disposed at the position a based on the backward tilting operation of the tilt lever 13, and at the position a, the hydraulic oil supply pipe 35 and the pipe 37a are connected, and the return pipe 32a and the pipe are connected. 37b, and the tilt cylinder 4 can be contracted. The tilt control valve 23 is arranged at the position c based on the forward tilt operation of the tilt lever 13. At the position c, the hydraulic oil supply pipe 35 and the pipe 37b are communicated with each other, and the pipe 37a is placed in communication with the return pipe 32a so that the tilt cylinder 9 can be extended. The tilt control valve 23 is disposed at the position b in FIG. 6 based on the neutral operation of the tilt lever 13, and cuts off the communication between the two pipes 37a, 37b, the hydraulic oil supply pipe 35, and the return pipe 32a. As a result, the state in which the movement of the hydraulic oil in the tilt cylinder 9 is prevented is maintained.

A control valve 38 and a pilot operation check valve 39 are provided in the middle of the pipe 37a. The pilot operation check valve 39 is provided between the control valve 38 and the rod chamber 9b so as to regulate the flow of hydraulic oil from the rod chamber 9b to the control valve 38. The control valve 38 is a one-way valve, and includes a direct-acting spool that opens and closes the conduit 37a. The control valve 38 is a normally-closed control valve, and a 2-port 2-position valve operated by pilot hydraulic pressure is used. The control valve 38 closes the conduit 37 a by the spring force of the spring 40 and the conduit 37 a. It is possible to switch between two positions, that is, the communicating position b. A passage 41 is formed in the spool so as to communicate with the conduit 37a when the spool is located at the position b. The passage 41 has an orifice. Pilot pressure to control valve 38 and pilot operated check valve 39 is supplied by proportional solenoid valve 43. Control valve 38
And the tilt cylinder 9 by the proportional solenoid valve 43.
An electromagnetic valve that opens and closes a conduit 37a that connects the control valve 23 with the tilt control valve 23 is configured.

The pilot pressure supply means for supplying the pilot pressure to the pilot operation check valve 39 and the proportional solenoid valve 43 is provided by the flow divider 2 of the hydraulic oil supply line 26.
On the upstream side of the pipe 8, the pipe is constituted by a pipe 44 branched from the hydraulic oil supply pipe 26. A pressure reducing valve 45 and a filter 46 are provided in the middle of the pipe 44.

The proportional solenoid valve 43 has a tank port T2 connected to the return line 32a, and an A port connected to the line 4
4 is connected. In addition, B of the proportional solenoid valve 43
The port communicates with a pressure chamber (not shown) provided at one end of the spool of the control valve 38. In the control valve 38, a pressure chamber (not shown) at the other end of the spool is connected to the return line 32.

The proportional solenoid valve 43 is a normally closed type solenoid valve. When the solenoid is demagnetized, the B port and the tank port T
2 is communicated. The proportional solenoid valve 43 is configured so that the amount of operation of the spool is proportional to the current supplied for excitation. When the solenoid is excited, the spool operates and the A port and the B port are connected. In communication, the pilot pressure set at the operating position of the spool is supplied to the spool of the control valve 38. By this pilot pressure, the spool of the control valve 38 is moved against the spring force of the spring 40.

The spool of the proportional solenoid valve 43 does not move until the command current value reaches the first predetermined value, the output pilot pressure is kept at zero, and the control valve 38 is kept at the opening of zero. After the command current value reaches the first predetermined value, the spool is moved in proportion to the command current value until the command current value reaches the second predetermined value, and the pilot pressure is supplied to the control valve 38 so that the control valve 38 The opening increases. And the command current value is the second
Above the predetermined value, the spool of the proportional solenoid valve 43 is held at the fully open position, and the control valve 38 is also held at the fully open state. Therefore, as shown in FIG. 2, the relationship between the opening degree of the control valve 38, ie, the flow rate L, and the command current value I is such that the flow rate is 0 until the command current value I becomes larger than the first predetermined values I1d, I1, I1u. And increases in proportion to the command current value from the first predetermined value I1d, I1, I1u to the second predetermined value I2d, I2, I2u, and reaches a maximum at the second predetermined value I2d, I2, I2u or more. Flow rate L
It becomes constant at MAX.

The lift control valve 22, the tilt control valve 23, the pilot operated check valve 39, the check valves 29, 3
6. The relief valves 30, 33, the control valve 38, the proportional solenoid valve 43, and the pressure reducing valve 45 are formed in one housing and constitute one control valve 48 as a whole.

Next, an electrical configuration for controlling the hydraulic circuit will be described. As shown in FIG. 3, a control device 49 for controlling the opening of the control valve 38, that is, the output pilot pressure of the proportional solenoid valve 43, controls the microcomputer 50, the input / output interfaces 56 and 57, the EEPROM 54b, and the solenoid drive circuit 52. Have. The microcomputer 50 includes a central processing unit (hereinafter referred to as C
PU) 53 and a read only memory (ROM) 54
a and readable and rewritable memory (RAM) 55
And an analog / digital conversion circuit (A / D conversion circuit) 51
And The CPU 53 functions as a control unit and a setting unit.

The ROM 54a stores (stores) various control programs and data necessary for executing the programs.
Have been. The control programs include, for example, a backward-tilt speed limiting control program, an adjustment mode program, and a backward-tilt speed limiting current value setting program used when setting the backward-tilt speed limiting current value. Further, the EEPROM 54b stores a command current value used at the time of limiting the backward tilt speed as data necessary for executing the backward tilt speed limiting control program.

The CPU 53 is connected to the potentiometer 15 and the pressure sensor 17 via the input interface 56 and the A / D conversion circuit 51, respectively. CPU53
Are connected to the elevation sensor 14, the forward tilt detection switch 18 and the rear tilt detection switch 19 via the input interface 56, respectively. CPU 53 is an output interface 5
7, and is connected to a solenoid drive circuit 52.

The solenoid drive circuit 52 transmits a pulse signal of a predetermined frequency to a transistor (not shown) to perform dither control based on a command signal output from the CPU 53.
Of the proportional solenoid valve 43, and a solenoid current (command current) of a predetermined value flows through the solenoid of the proportional solenoid valve 43.

The control device 49 has a current detection circuit 58. The current detection circuit 58 is electrically connected to the proportional solenoid valve 43 and connected to the CPU 53 via the input interface 56 and the A / D conversion circuit 51. The current detection circuit 58 detects a current flowing through the solenoid of the proportional solenoid valve 43, and outputs a voltage signal corresponding to the current amount to the A / D conversion circuit 51.

The controller 49 is connected to a matching switch 59 serving as a switching means for switching the control mode of the CPU 53 between the normal mode and the adjustment mode. The matching switch 59 is connected to the CPU 53 via the input interface 56. After the forklift 1 is manufactured, the matching switch 59 is switched to the adjustment mode only when the current value for limiting the backward tilting speed of the mast 3 is set, and is set to the normal mode when the user uses the forklift 1. .

The CPU 53 controls the sensors 14, 15, 1
7 and the output signals of the switches 18 and 19, and operates according to various control programs stored in the ROM 54a. When the tilt cylinder 9 is operated, a control command signal to the proportional solenoid valve 43 via the solenoid drive circuit 52 is provided. Is output. When the matching switch 59 is turned off, the CPU 53 operates in the normal mode in the proportional solenoid valve 4.
3, the proportional solenoid valve 43 is controlled in the adjustment mode when the matching switch 59 is turned on. The CPU 53 calculates the command current value actually flowing through the solenoid of the proportional solenoid valve 43 based on the output signal of the current detection circuit 58, and performs feedback control of the command current value.

When the backward tilt detection switch 19 is turned on while the matching switch 59 is turned on, the CPU 53 outputs the command current value to the proportional solenoid valve 43 so as to gradually increase. The CPU 53 calculates the backward tilt speed of the mast 3 based on the detection signal of the potentiometer 15 and sets the command current value when the backward tilt speed of the mast 3 reaches a predetermined value as a current value for limiting the backward tilt speed. It has become.

Next, the operation of the above-configured device will be described. When the engine E is operated and the hydraulic pump 25 is driven, the operating oil in the oil tank 24 is discharged to the operating oil supply pipe 26. Therefore, the pipeline 44 for supplying the pilot pressure is in a state where the pilot pressure can be supplied as soon as the hydraulic pump 25 is driven.

When the lift lever 12 is moved upward from the neutral position, the spool of the lift control valve 22 is arranged at the position a, and the hydraulic oil discharged from the hydraulic pump 25 is supplied to the bottom chamber 4b of the lift cylinder 4 and lifted. Cylinder 4
Extend and the fork 6 rises. When the lift lever 12 is lowered, the spool of the lift control valve 22 is disposed at the position c, and the hydraulic oil in the bottom chamber 4b
4, the lift cylinder 4 contracts and the fork 6 descends. The lift spool is arranged at the position b based on the neutral operation of the lift lever 12, the movement of the hydraulic oil in the lift cylinder 4 is prevented, and the fork 6 is held at the desired lift position.

When the tilt lever 13 is in the neutral position, the spool is held at the position b in FIG. 6, and the two pipes 37a and 37b are connected to either the hydraulic oil supply pipe 35 or the return pipe 32a. However, the communication is maintained in a disconnected state. Then, movement of the hydraulic oil of the tilt cylinder 9 is prevented, and the mast 3 is maintained at a desired tilt angle.

When the spool is disposed at the position c by the tilting operation of the tilt lever 13, the hydraulic oil supply pipe 35 and the pipe 37b are connected, and the pipe 37a and the return pipe 32a.
Is in a state of being communicated with. Also, the tilt lever 13
Is operated forward, the CPU 53 causes the forward lean detection switch 1
8 is input. Then, an excitation command signal is output from the CPU 53 to the proportional solenoid valve 43 via the solenoid drive circuit 52, and a pilot pressure is supplied to the control valve 38 and the pilot operation check valve 39 of the pipe 37a, and the operating oil is supplied to the pipe 37a. Can be flowed.
As a result, the hydraulic oil is supplied to the bottom chamber 9c via the hydraulic oil supply pipe 35 and the pipe 37b, and the hydraulic oil in the rod chamber 9b is supplied to the oil tank 24 via the pipe 37a and the return pipe 32a. Because of the discharge, the tilt cylinder 9 is extended, and the mast 3 is rotated toward the front side. If the mast 3 is rotated (tilted) forward from the vertical state, the mast 3
That is, the fork 6 is tilted forward.

When the spool is disposed at the position a by the tilting operation of the tilt lever 13, the hydraulic oil supply pipe 35 and the pipe 37a communicate with each other, and the pipe 37b and the return pipe 32a.
Is in a state of being communicated with. Also, the tilt lever 13
Is operated by the CPU 53, the CPU 53 informs the CPU 53 of the rearward tilt detection switch 1.
9 are input. Then, an excitation command current is output from the CPU 53 to the proportional solenoid valve 43 via the solenoid drive circuit 52, and a pilot pressure is supplied to the control valve 38 and the pilot operation check valve 39 so that the operating oil flows through the pipeline 37a. It is possible. As a result, the hydraulic oil is supplied to the rod chamber 9b through the hydraulic oil supply pipe 35 and the pipe 37a, and the hydraulic oil in the bottom chamber 9c is supplied to the oil tank 24 through the pipe 37b and the return pipe 32a. Because of the discharge, the tilt cylinder 9 is contracted, and the mast 3 is rotated rearward. When the mast 3 is rotated (tilted) rearward from the vertical state, the mast 3, that is, the fork 6 is tilted rearward.

When the CPU 53 receives an ON signal from the rearward tilt detection switch 19, the CPU 53 determines whether the output signal of the elevation sensor 14 is high (H) or low (L). If it is low, the backward tilt speed limitation is not performed, and a command signal for supplying a command current value for fully opening the proportional solenoid valve 43 is output to the solenoid drive circuit 52. As a result, the proportional solenoid valve 43 is fully opened, the control valve 38 is moved to the fully open position and held there, and the operating oil is supplied to the rod chamber 9b at a flow rate corresponding to the amount of operation of the tilt lever 13 by the operator. The mast 3 is pivoted rearward (backward tilt). Therefore, when the amount of tilting operation of the tilt lever 13 is maximized when the engine is fully opened, the mast 3 is tilted backward at the maximum speed.

On the other hand, if the output signal of the elevation sensor 14 is high, the CPU 53 executes the backward inclination speed limitation. That is,
The CPU 53 stores the EEPROM 54 in the proportional solenoid valve 43.
A command signal for supplying the command current value for limiting the backward tilt speed stored in b is output to the solenoid drive circuit 52. As a result, the proportional solenoid valve 43 is maintained at a predetermined opening, and the control valve 38 is also maintained at a predetermined opening. Therefore, even if the operator maximizes the amount of tilting operation of the tilt lever 13 when the engine is fully opened, the mast 3 is operated to tilt backward at a predetermined limited speed.

When the CPU 53 outputs a command signal to the solenoid drive circuit 52, it does not immediately output a command signal corresponding to a predetermined command current value, but takes a predetermined time for a predetermined command current as shown in FIG. Outputs a command signal to reach the value. Therefore, as indicated by the dashed line, the shock at the start of the backward tilting operation is smaller than when the command signal corresponding to the predetermined command current value is immediately output.

Further, the CPU 53 has the two detection switches 18,
If no ON signal is output from any of the control signals 19, the excitation command to the proportional solenoid valve 43 is not issued. Therefore,
Since the pilot pressure is not supplied to the control valve 38 and the pilot operation check valve 39, the flow of the hydraulic oil from the rod chamber 9b side to the tilt control valve 23 side is kept in a blocked state.

Next, a method of setting the current value for limiting the backward tilting speed of the mast 3 will be described. After the forklift 1 is manufactured, a current value for limiting the backward tilt speed is set as a part of various adjustment operations. Further, after the use of the forklift 1, when the entire control valve 49 is replaced or the parts related to the tilt cylinder 9 are replaced for maintenance or the like, the backward tilt speed limiting current value is set. When setting the backward leaning speed limiting current value, first move the mast 3 to the most forward leaning position, then, with the matching switch 59 switched to the adjustment mode, fully open the engine E without a load, and tilt the tilt lever. 13 is operated to the backward tilt position. When the matching switch 59 is switched to the adjustment mode, the matching switch 59 is in a state of outputting an ON signal.
When the tilt lever 13 is operated to tilt backward, an ON signal is output from the rearward tilt detection switch 19.

When the CPU 53 receives an ON signal from both the backward tilt detection switch 19 and the matching switch 59, the CPU 53 executes a backward tilt speed limiting current value setting program. At this time, the CPU 53 outputs a command signal to the solenoid drive circuit 52 to drive the tilt cylinder 9 at a speed lower than the normal backward tilt speed and to gradually increase the speed. For example, the CPU 53 outputs a command signal to the solenoid drive circuit 52 so that the command current value is increased by a fixed amount at regular intervals and supplied to the proportional solenoid valve 43. In this embodiment, CPU 53 is 2
Control is performed so that the command current value is increased by 0.05 A every 00 msec. Further, the CPU 53 inputs the detection signal of the potentiometer 15 and calculates a voltage change ΔV corresponding to a change amount of the tilt angle θ at each predetermined time.

Next, a method of setting the current value for limiting the backward tilting speed will be described in more detail with reference to the flowchart of FIG.
The CPU 53 outputs to the solenoid drive circuit 52 a command signal in which the command current value of the proportional solenoid valve 43 becomes a predetermined value (0.05 A) in step S1. And step S
In step 2, it is determined whether or not the voltage change amount ΔV of the potentiometer 15 for 200 msec is within a predetermined range (Vs1 to Vs2). Here, for example, Vs1 is about 0.18V, and Vs2 is about 0.2V. If the voltage change amount ΔV is not within the predetermined range in step S2, the CPU 53 proceeds to step S2.
Then, the process proceeds to step S3, where a command signal having a command current value that is 0.05 A larger than the previous value is output to the solenoid drive circuit 52, and then the process proceeds to step S2. In step S2, if the voltage change amount ΔV is within the predetermined range (a range having the allowable variation width including the backward tilt limit speed of the specification), the CPU 53 proceeds to step S4, in which the command current value at that time is tilted backward. It is set as the speed limiting current value Is. Then, the value is written into the EEPROM 54b as the backward inclination speed limiting current value Is. That is, if the characteristics of the solenoid valve are those indicated by the solid line in FIG. 2, the specified current value corresponding to the specified flow rate Ls is Is
The specified current value is Isd if the characteristic is indicated by the two-dot chain line.
If the characteristic is indicated by a broken line, the specified current value is Isu.

As shown in FIG. 2, since the backward inclination speed limiting current value Is is almost half the value of the maximum command current value If when fully opened, Step S2 and Step S3 are repeated a plurality of times. In step S4, the backward inclination speed limiting current value Is is set. In step S2, it is determined whether the voltage change amount ΔV is within a predetermined range. If it is determined whether the voltage change amount ΔV is equal to or more than a predetermined value Vs1, the flow rate L is determined to be a value larger than the allowable range. This is to prevent the backward inclination speed limiting current value Is from being set to a certain value. If the current value that is increased at one time is reduced, the current for restricting the backward inclination speed to a value larger than the allowable range of the flow rate L even if it is determined whether the voltage change amount ΔV is equal to or more than the predetermined value Vs1. Value Is
Can be prevented from being set.

When the engine E is fully opened (the hydraulic pump 25
The rotation of the mast 3 at the maximum speed is performed under the condition that the mast 3 can move at the fastest speed because the mast 3 can move fastest. It is. For example, when the backward tilting speed limiting current value is determined in a state other than the state where the engine is fully opened, the worker operates the tilt lever 1 when the engine is fully opened during the cargo handling work with the forklift 1.
This is because when the lever 3 is fully operated to the rearward tilt side, the mast tilts rearward faster than the predetermined rearward tilt limit speed, which is not preferable.

This embodiment has the following effects. (A) When setting the current value for limiting the backward tilt speed, the command current value to the solenoid valve (control valve 38 + proportional solenoid valve 43) is gradually increased, and the detection from the tilt angle detecting means (potentiometer 15) is performed. The signal is monitored, and a command current value when the backward tilt speed reaches a predetermined value is set as a current value for limiting the backward tilt speed. Therefore, the current of the solenoid valve-
It is possible to easily set the current value for the backward tilt speed limitation that realizes the backward tilt speed limit as specified even if the flow rate characteristics vary. As a result, the adjustment of the current value for limiting the backward tilting speed can be easily performed for each forklift 1, so that it is not necessary to increase the accuracy of the solenoid valve, and the structure can be simplified and the manufacturing cost can be reduced.

(B) In the adjustment mode for setting the current value for limiting the backward tilting speed, the tilt cylinder is operated at a speed lower than the normal backward tilting speed. Tilt speed is a predetermined value (predetermined range)
Can be determined with a margin.

(C) When setting the current value for limiting the backward tilting speed, the command current value to the solenoid valve is increased by a fixed amount at regular time intervals, and the voltage change of the tilt angle detecting means (potentiometer 15) during that time. Since the amount of ΔV is monitored and the current value for limiting the backward tilting speed is set, the control is simplified as compared with a case where the command current value is increased by a different amount at an arbitrary time.

(D) The amount of voltage change ΔV of the tilt angle detecting means (potentiometer 15) is monitored, and the command current value when the value is within a predetermined range (Vs1 to Vs2) is used for limiting the backward tilt speed. Since the current value is set as the current value, the backward inclination speed limiting current value I is set to a value at which the flow rate L becomes larger than the allowable range.
s can be reliably prevented from being set.

(E) Since the backward leaning speed limiting current value is set under the condition that the engine E is fully opened and no load is applied, the operator moves the tilt lever 13 backward when the engine is fully opened during the cargo handling operation. Even when the mast 3 is fully operated, the mast does not lean backward faster than the predetermined backward lean limit speed, and the shock when the mast 3 stops at the last inclined position is reliably reduced.

(F) The current value for limiting the backward inclination speed is EEPR
Since the current value is stored in the OM 54b and adjusted and set for each machine of the forklift 1, the tilting speed limiting current value can be easily and reliably stored in the storage unit. Also,
When the current value for limiting the backward tilting speed is newly set for replacement of the control valve 49 or the like, it is easy to rewrite the current value.

(G) Since the opening of the control valve 38 can be controlled by the pilot pressure supplied via the proportional solenoid valve 43, the opening of the control valve 38 is set when setting the current value for limiting the backward inclination speed. It is easy to gradually increase the command current value so that is gradually increased.

(H) In order to determine whether the lift is high or not in two stages to determine whether or not to limit the backward tilt speed, the CP
The calculation of U53 becomes easy. (I) Since the pilot pressure supply means for supplying the pilot pressure to the pilot operation check valve 39 and the proportional solenoid valve 43 is constituted by the pipeline 44 branched from the hydraulic oil supply pipeline 26 to the lift cylinder 4, the pilot The structure of the pressure supply means is simplified.

(V) Supply of hydraulic oil to the tilt cylinder 9 is controlled by a tilt control valve 23 (manual operation direction switching valve) for switching between supply and discharge of hydraulic oil to the tilt cylinder 9, and a tilt The control is performed by a control valve 38 provided in the middle of a pipe 37a connecting the control valve 23 and the tilt cylinder 9 to each other. Therefore, the operator can perform the tilting operation by substantially the same operation as the conventional manual operation valve, and can prevent the mast 3 from being tilted backward at an excessively high speed during the backward tilting operation.

(G) The hydraulic oil leaks from the sliding surface when a large pressure is applied to the spool valve, but is provided in a pipe line 37a connecting the tilt control valve 23 and the rod chamber 9b when the spool valve is not tilted forward. Since the pilot operated check valve 39 is closed, no large pressure acts on the tilt control valve 23. Therefore, when the mast 3 is held at the predetermined forward tilt position for a long time, leakage of hydraulic oil from the tilt control valve 23 or the control valve 38 is prevented, and the tilt angle is reliably maintained at the predetermined forward tilt angle.

The embodiments are not limited to the above, and may be embodied as follows, for example. The operation for finding the current value to be set as the backward tilt speed limiting current value is not completed in a single procedure shown in the flowchart of FIG. The average value of the current values (for example, two to several times) may be set as the current value for limiting the backward tilt speed. In this case, the reliability of the set backward tilt speed limiting current value is higher than the value set once.

When setting the current value for limiting the backward tilt speed, instead of increasing the command current value to the solenoid valve by a fixed amount at a time, the amount of one increase is initially set to be large, and the backward lean limit is specified. The rise amount is set to be small from near the flow rate corresponding to the speed. In this case, the time required for setting the current value for limiting the backward tilt speed is reduced.

When setting the current value for limiting the backward tilt speed, a configuration may be adopted in which the amount of increase in the command current value to be output next is determined from the voltage change amount ΔV of the tilt angle detecting means (potentiometer 15). Also in this case, the time required to set the current value for limiting the backward inclination speed is reduced.

The current value for limiting the backward tilting speed may be set under conditions other than the condition where the load is not loaded and the engine is not fully opened. The backward tilt speed limiting current value may be stored in a RAM provided with a backup battery, or may be stored in the ROM 54a, and the EEPROM 54b may be omitted. If you want to store it in RAM with power supply for backup,
Correction of the backward tilt speed limiting current value is facilitated.

The mast angle detecting means may be any as long as it can detect the tilt angle of the mast 3 from the reference position, and is not limited to the rotary potentiometer 15 for detecting the rotation angle of the tilt cylinder 9; A linear potentiometer that detects the amount of expansion and contraction of the cylinder 9, that is, the amount of protrusion of the piston rod 9a may be used. Further, the rotation angle of the shaft that rotates together with the mast 3 may be detected by a potentiometer or a rotary encoder.

The lift sensor 14 may be any sensor that can detect whether or not there is a portion to be detected, and a limit switch or an optical switch may be used instead of the proximity switch. A plurality of height sensors 14 are provided instead of two stages of whether the height is high or not, so that the height can be detected in three or four or more stages. When the load is loaded, the backward tilt speed is limited in three or more stages in combination with the load. In this case, the rearward tilting speed can be set to a more appropriate value as compared with a case where the rearward tilting speed is limited at two levels of lift regardless of the presence or absence of the load.

In this case, a sensor capable of continuously detecting the height may be used as the height detection means. For example, a conventionally used reel-type lift sensor is used as a sensor capable of continuously detecting the lift. Further, a sensor other than a reel-type lift sensor may be used as a sensor for continuously detecting the lift.

Instead of configuring the pilot pressure supply means with a pipe 44 branched from the hydraulic oil supply pipe 26,
A configuration is also possible in which a small-capacity hydraulic pump driven by the engine E is separately provided, and hydraulic oil for pilot pressure is supplied to the pipeline 44 from the hydraulic pump. In this case, the pressure reducing valve 45 may not be provided.

The pilot operated check valve 39 may be omitted. If the pilot operation check valve 39 is not provided, the control valve 38 may be provided in the conduit 37b connecting the bottom chamber 9c and the tilt control valve 23.

Although the lift control valve 22, the tilt control valve 23, the control valve 38, the proportional solenoid valve 43 and the like are formed integrally, the control valves 22, 23 and 38 may be formed separately.

Attachment other than the fork 6 as a cargo handling attachment, for example, a roll clamp used for transporting roll paper, a block clamp used for transporting blocks or stacking work, or a coil such as a wire or cable wound in a coil. Alternatively, the present invention may be applied to an industrial vehicle equipped with a ram or the like used for transporting a cylindrical load.

The present invention is not limited to an industrial vehicle using an engine as a driving source, but may be applied to an industrial vehicle using a battery as a driving source. In the above embodiment, the description has been given of the current value adjustment for the backward tilt speed control. However, the present invention may be applied to the current value adjustment for the forward tilt speed control. For example, in the related art, a throttle is provided in the tilt control valve 23 to regulate the forward tilting speed, but the control valve 38 is controlled by an instruction from the control means (CPU 53) to an opening degree which becomes a predetermined flow rate corresponding to the throttle. And In this case, the solenoid valve (proportional solenoid valve 43)
In order to prevent the variation in the pre-regulation tilt speed due to the variation in the forward tilt speed, it is necessary to set the current value for the forward tilt speed control for each forklift. At that time, it is possible to easily set the current value for controlling the forward leaning speed in a manner basically similar to that of the above-described embodiment.

When the matching switch 59 is turned on and the forward tilt detection switch 18 is turned on, the CPU 53 outputs a command current value to the proportional solenoid valve 43 so as to gradually increase. The CPU 53 calculates the forward tilt speed of the mast 3 based on the detection signal of the potentiometer 15, and sets the command current value when the forward tilt speed of the mast 3 reaches a predetermined value as a current value for limiting the forward tilt speed. . That is, FIG.
In the flowchart of FIG.
A value corresponding to the forward lean speed control is adopted as 1, Vs2, and a forward lean speed limiting current value is determined in step S4.
In this case, it is possible to easily set the forward tilting speed limiting current value of the solenoid valve that controls the supply flow rate of the working oil to the tilt cylinder. Therefore, even if the current-flow characteristics of the solenoid valve vary, it is possible to realize the forward lean speed limit as specified, and it is not necessary to increase the accuracy of the solenoid valve, thereby simplifying the structure and reducing the manufacturing cost. Further, the throttle of the tilt control valve 23 can be eliminated.

In this specification, the term “backward tilt speed” means not only the speed at which the mast moves backward than the vertical state (reference position), but also the movement of the mast from the forward tilt state toward the reference position. It also means the speed when you do.

The technical ideas (inventions) other than those described in the claims which can be understood from the above embodiments will be described below together with their effects. (1) The invention according to any one of claims 1 to 7, wherein the tilt angle detecting means outputs a voltage corresponding to the amount of tilt of the mast from a reference position. In this case, the backward inclination speed can be easily detected from the amount of change in the voltage.

(2) In the invention according to any one of claims 1 to 7 and (1), when setting the current value for limiting the backward tilting speed, the current value is stored in an EEPROM as a storage means. In this case, when changing the current value for limiting the backward tilting speed at the time of replacement or maintenance of the solenoid valve, storage (writing) and storage in the storage means are facilitated.

(3) In the invention according to any one of the first to seventh aspects, the solenoid valve is switched by a pilot pressure, and the pilot pressure is controlled by a proportional solenoid valve. In this case, it is easy to gradually increase the opening of the valve when setting the current value for limiting the backward tilting speed.

(4) In the invention according to any one of claims 1 to 4, the setting operation of the backward tilt speed limiting current value is started from a state in which the mast is arranged at the forward most inclined position. In this case, a large amount of rotation of the mast until the mast reaches the last tilt position can be ensured, and the setting operation becomes easy.

(5) An electromagnetic valve in which a mast for raising and lowering the cargo handling attachment is tiltably provided, and the flow rate of hydraulic oil supplied to the tilt cylinder for tilting the mast is adjusted by a command current from the control means. A method for setting a current value for controlling the forward tilting speed of a mast of an industrial vehicle controlled by a hydraulic pump at a predetermined rotational speed and operating the tilt cylinder forwardly in a state in which the solenoid valve is driven. While gradually increasing the command current value, the detection signal from the tilt angle detecting means capable of continuously detecting the mast tilt angle is monitored, and the command current value when the forward tilt speed reaches a predetermined value is increased. A method for setting a current value for controlling a forward tilting speed of a mast of an industrial vehicle, which is set as a current value for limiting a tilting speed. In this case, it is possible to easily set the forward tilting speed limiting current value of the solenoid valve that controls the supply flow rate of the hydraulic oil to the tilt cylinder. Therefore, even if the current-flow characteristics of the solenoid valve vary, it is possible to realize a forward lean speed limit as specified, and it is not necessary to increase the accuracy of the solenoid valve, thereby simplifying the structure and reducing the manufacturing cost. In addition, it is possible to eliminate the throttle of the tilt control valve.

[0093]

As described in detail above, claims 1 to 7 are provided.
According to the invention described in (1), it is possible to easily set the current value for limiting the backward tilting speed of the solenoid valve that controls the flow rate of the hydraulic oil supplied to the tilt cylinder. Therefore, the current of the solenoid valve-
Even if the flow rate characteristics vary, it is possible to realize the restriction of the backward tilt speed as specified, and it is not necessary to increase the accuracy of the solenoid valve, so that the structure can be simplified and the manufacturing cost can be reduced.

According to the second and sixth aspects of the present invention, the command current value is changed so as to increase by a fixed amount at regular time intervals. Control becomes easier as compared to

According to the third aspect of the present invention, the current value to be set as the backward leaning speed limiting current value is obtained a plurality of times, and the average value is set as the backward leaning speed limiting current value. The reliability is higher as compared with the case where the setting is performed in the number of setting processes.

According to the fourth aspect of the present invention, since the reference value for limiting the backward tilting speed is set at the maximum rotational speed of the hydraulic pump, the backward tilting speed surely becomes equal to or less than the predetermined speed when the backward tilting speed is limited. .

[Brief description of the drawings]

FIG. 1 is a flowchart showing a procedure for setting a current value for backward tilt speed limitation.

FIG. 2 is a diagram showing a relationship between a command current value and a flow rate.

FIG. 3 is a block diagram showing an electrical configuration of a control device.

FIG. 4 is a side view of the forklift.

FIG. 5 is a side view of a tilt operation lever.

FIG. 6 is a hydraulic circuit diagram for operating a tilt cylinder and a lift cylinder.

FIG. 7 is a diagram showing a relationship between a tilt angle and an output voltage of a potentiometer.

FIG. 8 is a diagram showing a map for controlling the backward inclination speed.

[Explanation of symbols]

1: Forklift as an industrial vehicle, 3: Mast, 6
... fork as cargo handling attachment, 9 ... tilt cylinder, 13 ... tilt lever as tilt operating means, 14 ... lift sensor as lift detecting means, 1
5 Potentiometer as mast angle detecting means, 1
9: rearward tilt detection switch as rearward tilt operation detecting means, 25
... hydraulic pump, 38 ... control valve constituting electromagnetic valve, 43 ...
Similarly, a proportional solenoid valve, 49 a control device, 53 a CPU as control means and setting means, 54b an EEPROM as storage means, 59 a matching switch as switching means.

Claims (7)

[Claims] An electromagnetic valve, which is provided with a mast for raising and lowering an attachment for cargo handling so as to be tiltable, and a flow rate of hydraulic oil supplied to a tilt cylinder for tilting the mast, the opening of which is adjusted by a command current from control means. A method for setting a current value for controlling the backward tilting speed of a mast of an industrial vehicle to be controlled, wherein a command to the solenoid valve is provided in a state where a hydraulic pump is driven at a predetermined rotational speed and the tilt cylinder is backwardly operated. While gradually increasing the current value, the detection signal from the tilt angle detecting means capable of continuously detecting the tilt angle of the mast is monitored, and the command current value at the time when the reverse tilt speed reaches a predetermined value is set to the backward tilt. A method of setting a current value for controlling the backward tilting speed of a mast of an industrial vehicle to be set as a current value for speed limitation. 2. The control means increases the command current value by a fixed amount at regular time intervals, and adjusts the command current value when the backward tilt speed during the interval becomes a predetermined value for limiting the backward tilt speed. 2. The method for setting a current value for controlling a rearward tilting speed of a mast of an industrial vehicle according to claim 1, wherein the current value is set as a current value. 3. The industrial vehicle according to claim 1, wherein a current value to be set as the backward lean speed limiting current value is obtained a plurality of times, and an average value thereof is set as the backward lean speed limiting current value. To set the current value for backward tilt speed control of the mast. 4. The method for setting a current value for controlling a rearward tilting speed of a mast of an industrial vehicle according to claim 1, wherein the predetermined rotation speed of the hydraulic pump is a maximum rotation speed. 5. An industrial vehicle in which a mast for raising and lowering an attachment for cargo handling is tiltably provided, and a flow rate of hydraulic oil supplied to a tilt cylinder for tilting the mast is controlled by an electromagnetic valve. Mast angle detecting means for detecting the tilt angle of the solenoid valve; switching means for switching the control means for controlling the opening of the solenoid valve between a normal mode and an adjustment mode; and whether or not the tilt operating means has been operated to the backward tilt position. And a command current value for controlling the opening of the solenoid valve according to predetermined conditions, the switching means is switched to an adjustment mode, and the backward-tilting operation detecting means Control means for outputting a command current value to the solenoid valve so as to gradually increase when a backward tilt detection signal is output from Setting means for calculating a backward tilt speed of the mast based on a detection signal of the mast angle detecting means, and setting the command current value when the value becomes a predetermined value as a current value for backward tilt speed limitation. Control device for industrial vehicles equipped with 6. The control device for an industrial vehicle according to claim 5, wherein the control means increases the command current value by a fixed amount at regular time intervals in the adjustment mode. 7. An industrial vehicle in which a mast for lifting and lowering an attachment for cargo handling is tiltably provided, and a flow rate of hydraulic oil supplied to a tilt cylinder for tilting the mast is controlled by a solenoid valve. Mast angle detecting means for detecting the tilt angle of the solenoid valve; switching means for switching the control means for controlling the opening of the solenoid valve between a normal mode and an adjustment mode; and whether or not the tilt operating means has been operated to the backward tilt position. When the switching means is switched to the adjustment mode and a rearward tilt detection signal is output from the rearward tilt detection signal, the tilt cylinder is rotated at a speed lower than the normal rearward tilting speed. Control means for operating the vehicle so as to gradually increase the speed.