JPH10265194A - Hydraulic controller of industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the constitution of a hydraulic circuit and to avoid with more certainty the inoperable state of cargo handling equipment due to the sticking of a valve. SOLUTION: A tilt control valve 29 which is switched manually with a tilt lever 13 is placed on the oil passages 26b, 36a, 36b, 35 of the tilt cylinder 9 of a forklift. A solenoid valve 39 comprising a control valve 37 opening and closing the oil passage of the line 36a and a proportional solenoid valve 38 controlling pilot pressure used for operating the control valve 37 is provided on the part of the line 36a between the tilt control valve 29 and the tilt cylinder 9. The proportional solenoid valve 38 is controlled by a controller to open and close, thus controlling stopping and speed of a mast independently of the operation of the tilt lever 13. In the event that the tilt control level 29 has stuck, switching can be done by operating the tilt lever 13 with a rather strong force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for an industrial vehicle, such as a forklift, provided for operating a cargo handling device, such as a fork, in response to an operation of an operation lever.

[0002]

2. Description of the Related Art In a forklift, for example, the lift cylinder is driven to extend and retract by operating a lift lever, and the fork is raised and lowered. By operating the tilt lever, the tilt cylinder is driven to extend and retract to tilt the mast. 2. Description of the Related Art A hydraulic control device for driving and controlling a lift cylinder and a tilt cylinder is provided in a vehicle.

Conventionally, two main methods have been known as control systems for opening and closing an oil passage of a hydraulic cylinder in response to operation of a cargo handling lever. One is a manual method using a manual control valve (manual switching valve) that is manually switched by operating a cargo handling lever. The other is an electric control system in which the operation of a cargo handling lever is electrically detected by a switch, and a controller switches an electromagnetic control valve (electromagnetic switching valve) (Japanese Patent Laid-Open No. 7-61792, etc.). .

For example, in an apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 7-61792, an automatic horizontal stop which causes a controller to control an electromagnetic control valve independently of an operation of a cargo handling lever by an operator, for example, stops a fork in a horizontal posture. The control and the tilting speed control of the mast for controlling the opening of the electromagnetic valve for flow control provided on the oil passage of the tilt cylinder are performed.

[0005]

By the way, regardless of the difference between the manual control valve and the electromagnetic control valve, the thermal expansion accompanying the temperature rise of the hydraulic oil and the foreign matter in the oil that has entered between the spool and the body are not affected. Due to the cause, sticking (stick) that causes excessive friction between the spool and the body may occur. With a configuration using a manual control valve, even if sticking occurs, the operator can switch the cargo handling lever by operating the cargo handling lever with some force. However, in the electric control method, if there is a frictional resistance exceeding the driving force of the spool determined by a predetermined current value set to operate the electromagnetic control valve, the electromagnetic control valve becomes inoperable. Therefore, there is a possibility that a situation in which the lift cylinder or the tilt cylinder does not move even though the cargo handling lever is operated may occur.

In order to avoid such a situation, it is conceivable to take measures such as securing a large clearance (clearance) between the spool and the body of the electromagnetic control valve so as to prevent sticking from occurring. In addition, leakage of hydraulic oil due to an increase in clearance is a new problem.

Further, since the manual control method has been widely used in the past, if an electric control method using an electromagnetic control valve is adopted, a significant design change such as replacing the manual control valve with an electromagnetic control valve is required. There is a problem that conventional parts such as a manual control valve cannot be utilized. Furthermore, in a configuration that uses an electromagnetic control valve, stop control of the fork and mast can be performed by closing the electromagnetic control valve.However, if speed control of the fork or mast is attempted, flow control is performed on the oil passage. A separate solenoid valve must be provided, and the hydraulic circuit becomes complicated and the control becomes complicated.

The present invention has been made in view of the above problems, and a first object of the present invention is to simplify the hydraulic circuit configuration and to further prevent a situation in which cargo handling equipment becomes inoperable due to sticking of a valve. An object of the present invention is to provide a hydraulic control device for an industrial vehicle that can be used. A second object is to stop the cargo handling equipment in a horizontal posture by controlling the opening and closing of an oil passage of a hydraulic cylinder. A third object is to limit the backward tilting speed of the mast according to the lift by controlling the flow rate of the oil passage of the hydraulic cylinder. A fourth object is to mitigate an impact when the mast stops at a predetermined stop angle by controlling a flow rate of an oil passage of a hydraulic cylinder. A fifth object is to prevent the cargo handling equipment from moving due to its weight or the like when a third party erroneously operates the operation unit during key-off. A sixth object is to suppress a natural descent and a natural forward lean of the cargo handling equipment. A seventh object is to improve the positional accuracy when stopping and controlling the cargo handling equipment.

[0009]

In order to achieve the first object, according to the first aspect of the present invention, a hydraulic control device for an industrial vehicle is operated by operating an operation section for operating cargo handling equipment. A manual switching valve that is switched and driven, a hydraulic cylinder for driving the cargo handling device, an electromagnetic valve provided in series with the manual switching valve on an oil passage of the hydraulic cylinder, and a device for controlling the cargo handling device. A detection unit for obtaining a required detection value and a control unit for controlling the solenoid valve based on the detection value obtained from the detection unit are provided.

According to a second aspect of the present invention, in the first aspect of the invention, the solenoid valve is an electromagnetic proportional control valve. In the invention described in claim 3, in the invention described in claim 2, the electromagnetic proportional control valve is a control valve provided in series with the manual switching valve on an oil passage of the hydraulic cylinder;
And a proportional solenoid valve for adjusting the pilot pressure required to drive the control valve.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the electromagnetic valve includes a control valve capable of switching to a plurality of openings, and a control valve for switching the control valve to a plurality of openings. And a plurality of on / off valves combined so that the required pilot pressure can be selected stepwise.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the hydraulic cylinder is for tilting a mast for supporting the loading and unloading equipment so as to be able to move up and down. belongs to.

According to a sixth aspect of the present invention, in order to attain the second object, in the fifth aspect of the invention, the detecting means is operated by an operation switch operated when the cargo handling equipment is automatically stopped horizontally. And a tilt angle detector for detecting a tilt angle of the mast, wherein the control means, when inputting a signal indicating that the operation switch is operated, based on a detection value from the tilt angle detector. An automatic level stop means for performing stop control for closing the solenoid valve so as to stop the mast at a horizontal setting angle at which the cargo handling equipment is leveled is provided.

According to a seventh aspect of the present invention, in order to achieve a third object, in the fifth aspect of the present invention, the detecting means includes a height detector for detecting a height of the cargo handling equipment; A rearward tilt operation detector for detecting that the operation unit has been rearwardly tilted, wherein the control unit receives a detection signal indicating that the operation unit has been rearwardly tilted from the rearward tilt operation detector, From the backward tilt speed of the mast set to at least two stages that are slower as the lift is higher, determine the backward tilt speed according to the lift at that time based on the detection value from the lift detector, There is provided a rearward tilting speed control means for adjusting the opening of the solenoid valve to an opening corresponding to the rearward tilting speed.

In order to achieve a fourth object, according to the invention described in claim 8, in the invention described in claim 5, the detecting means includes an inclination angle detector for detecting an inclination angle of the mast, The control means, when recognizing that the inclination angle of the mast has reached a deceleration range set before the stop angle based on the detection value from the inclination angle detector, to reduce the inclination speed of the mast. An impact mitigation control means for adjusting the opening of the solenoid valve to be narrow is provided.

According to a ninth aspect of the present invention, in the invention according to the eighth aspect, in the hydraulic control device for an industrial vehicle according to the eighth aspect, the horizontal set angle in the sixth aspect, It is at least one of the rearward inclination restricting angles of the mast.

According to a tenth aspect of the present invention, in order to achieve a fifth object, in the first aspect of the present invention, the solenoid valve is a normally closed valve, and An operation detecting means for detecting that the unit has been operated is provided, and the control means, upon input of a detection signal from the operation detecting means, opens the solenoid valve at times other than a predetermined closing time.

In order to achieve the sixth object, according to the invention described in claim 11, in the invention described in any one of claims 1 to 10, an oil passage connecting the manual switching valve and the hydraulic cylinder is provided. In a direction in which a pilot check valve operated by hydraulic pressure from a hydraulic pump driven by starting of a vehicle can prevent displacement of a piston rod of the hydraulic cylinder due to its own weight of the cargo handling device, It is provided near the hydraulic cylinder.

According to a twelfth aspect of the present invention, in order to attain a fifth object, there is provided the invention as set forth in any one of the first to eleventh aspects, further comprising a plurality of hydraulic cylinders for cargo handling. Of the hydraulic cylinders described above, the second hydraulic cylinder and the second manual switching valve for opening and closing the hydraulic passage of the second hydraulic cylinder are provided on the hydraulic passage of the second hydraulic cylinder that does not include the solenoid valve on the hydraulic passage. In the meantime, a second pilot check valve operated by hydraulic pressure from a hydraulic pump driven by starting of the vehicle is provided in a direction capable of preventing displacement of a piston rod of the second hydraulic cylinder due to its own weight of the cargo handling equipment. ing.

According to a thirteenth aspect of the present invention, in order to achieve a seventh object, in the first aspect of the present invention, the electromagnetic valve comprises the cargo handling equipment in the hydraulic cylinder. It is provided on an oil passage connected to the chamber on the side receiving the load pressure from

(Operation) According to the first aspect of the present invention,
An electromagnetic valve provided in series with the manual switching valve on the oil passage of the hydraulic cylinder is controlled by the control means based on the detection value from the detection means, so that the cargo handling equipment is controlled independently of the operation of the operation unit. You. That is, by controlling the opening and closing of the oil passage of the hydraulic cylinder by the solenoid valve, the stop control of the cargo handling equipment becomes possible. Further, the flow rate of the oil passage of the hydraulic cylinder is adjusted by the solenoid valve, so that the speed of the cargo handling equipment can be controlled. It is relatively simple to configure simply by adding an electromagnetic valve to the oil passage of a conventionally used manual switching valve, and parts such as a manual switching valve used in a general-purpose hydraulic circuit can also be used. In the case of an electric control system without a manual switching valve, if the valve sticks (sticks) due to thermal expansion of the valve or foreign matter mixed in the gap between the spool and the body,
There was a concern that the cargo handling equipment would become inoperable.However, even if sticking occurs, it is possible to switch the manual switching valve by manually operating the operation unit with some force. It is easy to avoid the problem of inoperability.

According to the second aspect of the present invention, since the solenoid valve is an electromagnetic proportional control valve, the opening and closing control for opening and closing the oil passage of the hydraulic cylinder and the flow control for adjusting the flow rate of the oil passage are one.
It can be performed with two electromagnetic proportional control valves. That is, stop control and speed control of the cargo handling equipment can be performed with only one electromagnetic proportional control valve.

According to the third aspect of the present invention, the pilot pressure for operating the control valve provided on the oil passage of the hydraulic cylinder is controlled by controlling the current of the proportional solenoid valve. The current required for driving is small.

According to the fourth aspect of the present invention, the pilot pressure is switched stepwise by a combination of the switching states of the plurality of on / off valves, so that the control valve is stepped to a predetermined opening degree based on the pilot pressure. Is switched. Therefore,
Even if a proportional solenoid valve is not provided, stop control and stepwise speed control of cargo handling equipment can be performed with a simple configuration combining a plurality of on / off valves.

According to the fifth aspect of the present invention, the hydraulic cylinder is for tilting the mast for supporting the loading / unloading equipment up and down, so that at least one of the mast stop control and the tilt speed control is provided. One control becomes possible.

According to the sixth aspect of the present invention, when the operation unit is operated in a direction to bring the cargo handling equipment closer to the horizontal and the signal for operating the operation switch is input while the mast is tilting, the automatic leveling is performed. The stopping means closes the solenoid valve so that the mast is stopped when the inclination angle of the mast reaches a horizontal setting angle for leveling the cargo handling equipment based on a value detected by the inclination angle detector. As a result, the cargo handling equipment automatically stops in the horizontal posture simply by continuing to operate the operation unit in a direction in which the cargo handling equipment is brought closer to the horizontal while the operation switch is operated.

According to the seventh aspect of the present invention, when the rearward tilt operation detector detects that the operation section has been rearwardly tilted, the rearward tilt speed control means delays in advance as the lift is higher. From the backward tilt speeds of the mast set in at least two stages, determine the backward tilt speed according to the lift at that time based on the value detected from the lift detector, and the opening according to this backward tilt speed Adjust the opening of the solenoid valve. Accordingly, the higher the lift, the more the mast is inclined backward.

According to the eighth aspect of the present invention, the impact mitigation control means determines that the inclination angle of the mast has reached the deceleration range set before the stop angle based on the detection value from the inclination angle detector. Is recognized, the opening of the solenoid valve is adjusted to be narrow to reduce the tilting speed of the mast. As a result, the impact when the mast stops at the predetermined stop angle is reduced.

According to the ninth aspect of the present invention, the sixth aspect of the present invention provides
In the automatic horizontal stop control by the automatic horizontal stop means in the above, the impact when the cargo handling equipment stops in the horizontal posture is reduced. Further, the impact at the time when the mast reaches the backward leaning restriction angle and the backward lean is completed is reduced.

According to the tenth aspect of the present invention, when the key is turned off (for example, when the engine is stopped), the oil passage of the hydraulic cylinder is shut off by the solenoid valve that is a normally closed valve. Even if the manual switching valve is switched to the open state by operating, the cargo handling equipment is prevented from moving due to its weight or the like. Also, at key-on,
When a detection signal indicating that the operation unit has been operated is input from the operation detection unit, the control unit opens the solenoid valve except for a predetermined valve closing timing to open the oil passage.

According to the eleventh aspect, when the key is turned off (for example, when the engine is stopped), the pilot check valve is kept closed, and the oil passage between the solenoid valve and the hydraulic cylinder is more reliably shut off. . As a result, it is possible to prevent the operating oil in the hydraulic cylinder from leaking through the gap between the spool of the manual switching valve or the solenoid valve and the body during the key-off. Therefore,
Natural descent and natural leaning of the cargo handling equipment at the time of key-off are more reliably prevented. In addition, when the solenoid valve is a normally open valve, even if a third party erroneously operates the operation unit to open the manual switching valve during key-off, the pilot check valve opens the hydraulic passage of the hydraulic cylinder. Because of the blocking, it is possible to prevent the cargo handling equipment from moving due to its weight or the like.
On the other hand, at the time of key-on (for example, when the engine is driven), the pilot check valve is opened by the pilot pressure based on the discharge pressure of the hydraulic pump, and the oil passage is opened.

According to the twelfth aspect, at the time of key-off (for example, when the engine is stopped), the second pilot check valve provided on the oil passage between the second hydraulic cylinder and the second manual switching valve is closed. The valve is held and shuts off the oil passage between the second hydraulic cylinder and the second manual switching valve. Therefore, even if a third party erroneously operates the operation unit during key-off to open the second manual switching valve, it is possible to prevent the cargo handling equipment from moving due to its weight or the like.

According to the thirteenth aspect of the present invention, when the solenoid valve is opened, the hydraulic oil in the chamber to which the solenoid valve is connected is pushed out by receiving the load pressure from the cargo handling equipment, and is released. Since the equipment moves, if the solenoid valve is closed to stop the cargo handling equipment based on the detection signal from the detecting means, the cargo handling equipment stops immediately and the positional accuracy is easily obtained. If the hydraulic cylinder is for tilting the mast, the accuracy of the stop position of the mast is easily obtained. For example, in the automatic horizontal stop control according to claim 6, it is easier to stop the cargo handling equipment in a horizontal posture.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 to 6 show a first embodiment in which the present invention is embodied in a hydraulic control device for cargo handling of a forklift.
It will be described based on.

As shown in FIG. 4, a forklift 1 as an industrial vehicle has a mast
Is erected. The mast 3 includes a pair of left and right outer masts 3a supported so as to be tiltable back and forth with respect to the vehicle body frame 2, and inner masts 3b sliding up and down.
Consists of A lift cylinder 4 as a second hydraulic cylinder is disposed at the rear of each outer mast 3a. The tip of the piston rod 4a of the lift cylinder 4 is connected to the upper part of the inner mast 3b. A chain 7 having one end fixed to the body of the lift cylinder 4 or the upper part of the outer mast 3a and the other end connected to a lift bracket 6 is mounted on the chain wheel 5 supported on the upper part of the inner mast 3b. The fork 8 as a cargo handling device is lifted and lowered by the expansion and contraction of the lift cylinder 4 together with the lift bracket 6 suspended from the chain 7.

The mast 3 is connected to and supported by the body frame 2 via a pair of left and right tilt cylinders 9 as hydraulic cylinders. Tilt cylinder 9
Has a base end rotatably connected to the vehicle body frame 2 and is rotatably connected to the outer mast 3a at a distal end of the piston rod 9a. The mast 3 tilts back and forth as the tilt cylinder 9 is driven to expand and contract.

The driver's cab 10 has a steering wheel 11 in front of it.
Lift lever 12 and tilt lever 1 as operation unit
3 (however, in FIG. 4, both levers 12, 1 are provided).
3 are shown superimposed). Lift lever 12
Is operated when raising and lowering the fork 8, and the tilt lever 13 is operated when tilting the mast 3.

As shown in FIG. 3, near the operation force transmitting mechanism 13a of the tilt lever 13, a tilt lever 13 is provided.
A forward tilt detection switch 14 that constitutes operation detection means for detecting that the user has tilted forward, and a tilt lever 13
A rearward tilt detection switch 15 as a rearward tilting operation detector is provided, which constitutes detecting means and operation detecting means for detecting that the rearward tilting operation has been performed. Both switches 14 and 15 are, for example, micro switches. The forward tilt detection switch 14 is turned on when the tilt lever 13 is tilted forward, and the rear tilt detection switch 15 is turned on.
Turns on when 3 is tilted backward. When the tilt lever 13 is in the neutral position, the switches 14 and 15 are turned off.
Are both turned off.

An operation switch 16 is provided on the knob 13b of the tilt lever 13. The operation switch 16 is used to operate the tilt lever 13 when the fork 8 is operated.
Is to be operated by the operator when the user wants to automatically stop at the horizontal position.

As shown in FIG. 2, on the upper part of the outer mast 3a, a height sensor 17 as a height detector which constitutes a detecting means is provided. The lift sensor 17 is, for example, a proximity sensor. The lift sensor 17 is turned on when the fork 8 is at a high lift higher than a predetermined height, and is turned off when the fork 8 is at a low lift below a predetermined height. Further, a rotation potentiometer 18 as a tilt angle detector is provided on the vehicle body frame 2 as a detecting means for detecting the attitude angle of the tilt cylinder 9 and indirectly detecting the tilt angle of the mast 3. A rotating piece 18a fixed to the input shaft of the potentiometer 18 so as to be integrally rotatable has a pin 9b protruding from the tilt cylinder 9.
, And a detection signal corresponding to the attitude angle of the tilt cylinder 9 is output from the potentiometer 18. A pressure sensor 19 for detecting the oil pressure of the bottom chamber 4b is provided below the lift cylinder 4. The pressure sensor 19 outputs a detection signal corresponding to the load of the fork 8.

FIG. 1 shows a hydraulic circuit of a cargo handling system provided in the forklift 1. As shown in the figure, a hydraulic pump 21 for pumping and discharging hydraulic oil from an oil tank 20 to each of the cylinders 4 and 9 is driven by an engine E (shown in FIG. 4). The hydraulic oil from the hydraulic pump 21 is discharged to the flow divider 22 through the pipe 23. The flow divider 22 is for increasing the operating oil from the hydraulic pump 21 to a predetermined pressure or more and then diverting the hydraulic oil to a hydraulic circuit for the cargo handling system and a hydraulic circuit for the steering system. The pressure oil diverted from the flow divider 22 to the steering system is returned to the oil tank 20 via a pipe 25 passing through a steering valve 24.

The hydraulic oil supply line 26 through which the pressure oil diverted from the flow divider 22 to the cargo handling system passes is connected to a return line 27 returning to the oil tank 20 and is used for a lift as a second manual switching valve. The control valve 28 and the tilt control valve 29 as a manual switching valve are connected to the hydraulic oil supply line 26.
It is arranged in series above.

The lift control valve 28 is a seven-port three-position switching valve, and its spool is mechanically connected to the lift lever 12. Lift the lift lever 12
By performing the lowering operation, the lift control valve 28 is set to a, b,
The state can be manually switched to the three states c.

The lift control valve 28 has a branch line 26 a branched from the hydraulic oil supply line 26 and the return line 2.
7 is connected to a conduit 30 connected to the bottom chamber 4b of the lift cylinder 4. When the lift control valve 28 is switched to the position a (up position), the branch pipe 26a and the pipe 30 communicate with each other to supply hydraulic oil to the bottom chamber 4b, and the lift cylinder 4 is extended. In addition, lift control valve 2
When the position 8 is switched to the position c (down position), the line 30 communicates with the return line 27, and the hydraulic oil in the bottom chamber 4b is discharged to the oil tank 20 through the lines 30, 27, and the lift cylinder 4 shrinks. Further, when the lift control valve 28 is at the position b (neutral position), the pipe 30 is disconnected from the pipes 26a and 27, and the piston rod 4a of the lift cylinder 4 is held at a predetermined amount. At the position c, the hydraulic oil in the bottom chamber 4b is discharged by the load pressure acting on the piston rod 4a.

The pressure transmission line 32 for transmitting the discharge pressure of the hydraulic pump 21 for use in pilot control is connected to the line 23.
It is connected to the. The pressure reducing valve 33 provided on the pressure transmission line 32 is for adjusting the discharge pressure of the hydraulic pump 21 to a predetermined pilot pressure (set pressure). A pilot check valve 34 as a second pilot check valve provided on the pipe 30 is operated by the hydraulic pressure of the pressure transmission pipe 32,
When the oil pressure becomes equal to or higher than a predetermined pressure after the engine is started (for example, after 1 to 2 seconds), the valve is held open. That is, the pilot check valve 34 is kept closed when the key is turned off (engine is stopped), opens only when the key is turned on (engine is started), and has a function of stopping the flow of hydraulic oil from the bottom chamber 4b in the key-off state.

The tilt control valve 29 is a 6-port 3 position switching valve, and its spool is mechanically connected to the tilt lever 13. Tilt lever 13 backward
By performing the neutral / forward tilt operation, the tilt control valve 29 can be manually switched to the three states a, b, and c. The tilt control valve 29 includes a hydraulic oil supply line 26.
A branch line 26b branched from the outlet, a discharge line 35 connected to the return line 27, a line 36a connected to the rod chamber 9d as a chamber of the tilt cylinder 9, and a line 36b connected to the bottom chamber 9e are connected. ing.

A control valve 37 for opening and closing an oil passage of hydraulic oil flowing through the pipe 36a and a proportional solenoid valve 38 for controlling a pilot pressure for operating the control valve 37 are provided on the pipe 36a. An electromagnetic valve 39 as an electromagnetic proportional control valve is provided. The solenoid valve 39 is provided on a tilt-type oil passage in order to perform stop control and speed control of the mast 3 described later, which are performed independently of the operation of the tilt lever 13. The opening of the control valve 37 is controlled by the current value (solenoid current value) flowing through the proportional solenoid valve 38.

The control valve 37 is a two-port, two-position one-way normally closed valve, and is closed by the urging force of the spring 40 when the pilot pressure is less than a predetermined value. Proportional solenoid valve 3
Reference numeral 8 denotes a normal close valve, which closes by the urging force of the spring 41 when the solenoid current value is less than a predetermined value Io. The proportional solenoid valve 38 is connected to the pressure transmission line 32, and applies a pilot pressure to the control valve 37 according to the opening determined by the current value. Here, the solenoid valve 39 is divided into the control valve 37 and the proportional solenoid valve 38 because the solenoid current required for control can be smaller than when a direct acting valve is employed.

In the state where the control valve 37 is opened, when the tilt control valve 29 is switched to the position a (backward tilt position), the pipelines 26b and 36a communicate with each other, and the operating oil is supplied to the rod chamber 9.
d, the hydraulic fluid in the bottom chamber 9e is discharged to the oil tank 20 through the pipelines 36b, 35, and 27, and the tilt cylinder 9 contracts. When the tilt control valve 29 is switched to the position c (forward tilt position) in a state where the control valve 37 is opened, the pipes 26b and 36b communicate with each other, and the hydraulic oil is supplied to the bottom chamber 9.
e, the pipes 36a, 35 communicate with each other, the hydraulic oil in the rod chamber 9d is discharged to the oil tank 20 through the pipes 36a, 35, 27, and the tilt cylinder 9 is extended. . The tilt control valve 29
Is in the position b (neutral position), each of the conduits 36a,
36b is cut off from the conduits 26b and 35, so that the piston rod 9a of the tilt cylinder 9 is maintained at a predetermined protrusion amount. At the position c (the forward tilt position) of the tilt control valve 29, since the flow path is restricted by the orifice 42, the opening of the control valve 37 is narrowed, and the flow rate is limited by the opening of the control valve 37. Unless it comes to
The forward leaning speed of the mast 3 is set to be relatively lower than the backward leaning speed.

A pilot check valve 43 is provided on the conduit 36a between the control valve 37 and the tilt cylinder 9 in such a direction as to be able to prevent the hydraulic oil from flowing out of the rod chamber 9d in a closed state. The pilot check valve 43 operates at the same pilot pressure that operates the control valve 37, and is set to open at a pilot pressure lower than the control valve 37 starts to open.

A relief valve 44 is provided on a line 45 connecting the hydraulic oil supply line 26 and the return line 27, and a relief valve 46 is provided on the lift control valve 28 and the return line 2.
7 is provided on a pipe line 47 connecting to the pipe 7. Line 47 is
When the lift control valve 28 is at the b position (neutral position) or the c position (down position) where the hydraulic oil supply pipe 26 is not shut off, the lift control valve 28 communicates with the pipe 48 branched from the pipe 45. I have.

When the lift control valve 28 is switched to the position a (up position) at which the lift control valve 28 shuts off the hydraulic oil supply line 26, the pressure oil flowing through the oil passage of the lift system increases the lift set pressure. This is for allowing the hydraulic oil to escape so that When the tilt control valve 29 is switched to either the a position (backward tilt position) or the c position (forward tilt position) in which the tilt control valve 29 shuts off the hydraulic oil supply line 26, the tilt valve of the tilt system is used. This is for releasing the hydraulic oil so that the pressure oil flowing through the oil passage becomes the tilt set pressure. The check valves 49, 50, and 51 are for preventing backflow of hydraulic oil. The filter 52 is provided for removing dust in oil because the proportional solenoid valve 38 is precise. The pipes 26b, 36a,
36b and 35 constitute a tilt type oil passage.

Next, the electrical configuration of the hydraulic control device will be described. As shown in FIG. 2, the controller 53 as an opening of the control valve 37, that is, a control unit for controlling the output pilot pressure of the proportional solenoid valve 38, an automatic horizontal stop unit, a backward tilt speed control unit, and an impact relaxation control unit, Microcomputer 54, analog / digital conversion circuit (A / D
(A conversion circuit) 55 and a solenoid drive circuit 56. The microcomputer 54 includes a central processing unit (hereinafter referred to as a CPU) 57 and a read-only memory (ROM).
58a and an EEPROM (Electrical Erasable Pro)
It has a grammable ROM 58b, a readable and rewritable memory (RAM) 59, an input interface 60 and an output interface 61.

The ROM 58a stores (stores) various control programs and data necessary for executing the programs.
Have been. The EEPROM 58b stores, as data necessary for executing the forward leaning angle control program, a map representing the relationship between the lift and the load and the maximum allowable forward leaning angle (hereinafter, referred to as forward leaning restraining angle). For example, as shown in FIG. 5, two types of maps are prepared, one for a high lift (solid line) and one for a low lift (chain line). Corners are set.

The horizontal set angle is stored in the EEPROM 58b as data necessary for executing the automatic horizontal stop control program. The horizontal setting angle is a value corresponding to the detection value of the potentiometer 18 when the fork 8 is in the horizontal posture.

The EEPROM 58b stores a map representing the relationship between the lift and the solenoid current value as data necessary for executing the backward tilt speed control program. The solenoid current value is a current value for controlling the proportional solenoid valve 38, and the opening of the control valve 37 is controlled so as to be substantially proportional to this current value. In this embodiment,
As shown in FIG. 6, the current value In is set when the lift is low, and the current Im (where In> Im) is set when the lift is high. The backward tilting speed of the mast 3 is switched between two stages according to the lift. It is supposed to be.

The deceleration start angle is set in the EEPROM 58b as data necessary for executing the shock mitigation control program. The shock mitigation control is control for decelerating the mast 3 just before a predetermined stop angle to reduce the shock at the time of stop. In the present embodiment, when the mast 3 is decelerated at a constant deceleration (tilt), the speed “0” at a predetermined stop angle.
The deceleration start angle determined for each stop angle from the tilting speed of the mast 3 before the start of deceleration is set. The deceleration start angle is a forward leaning restriction angle, a horizontal set angle, and a backward leaning restriction angle (mast inclination angle at the end of the backward tilt of the tilt cylinder 9)
Is set for each stop angle. For example, when the mast 3 is tilted rearward, as shown in FIG. 6, the rearward tilting speed is switched in two stages in accordance with the lift. The deceleration start angles θ1 and θ2 are set according to. In addition, EEPR
The data of the OM 58b is determined by a setting operation unit (not shown) in consideration of a vehicle model, a vehicle application, a variation in device accuracy, and the like.
By operating the, it can be set individually for each machine.

Potentiometer 18 and pressure sensor 19
Is connected to the CPU 57 via the A / D converter 55 and the input interface 60. The elevation sensor (proximity sensor) 17, the forward tilt detection switch 14, the rear tilt detection switch 15, and the operation switch 16 are connected to the CPU 57 via the input interface 60.

The solenoid drive circuit 56 is connected to the CPU 57 via the output interface 61. CP
U57 outputs a command value for commanding a solenoid current value for controlling the current value of the proportional solenoid valve 38 to the solenoid drive circuit 56. Then, the solenoid drive circuit 56 controls the current flowing through the proportional solenoid valve 38 based on the command value.

Next, the operation of the hydraulic control device configured as described above will be described. At the time of key-off (engine stop), the drive of the hydraulic pump 21 is stopped and the pressure transmission line 3
The pilot check valve 3
4, 43 are kept in the valve closed state. Therefore, at the time of key-off, the natural fall of the fork 8 and the natural forward inclination of the mast 3 are more reliably prevented. Further, even if a third party erroneously operates the lift lever 12 at the time of key-off, the fork 8 does not lower due to the closing of the pilot check valve 34. Also, even if a third party erroneously operates the tilt lever 13 at the time of key-off, the control valve 37 and the pilot check valve 4
By closing the valve 3, the mast 3 does not lean forward.

When the key is turned on, the engine E is started, and the driving of the hydraulic pump 21 is started. After the engine is started, the pilot check valve 34 is opened when the oil pressure in the pressure transmission line 32 becomes equal to or higher than a predetermined pressure. Then, for example, after 1 to 2 seconds from the start of the engine, the hydraulic pressure of the pressure transmission line 32 reaches the pilot set pressure. The hydraulic oil discharged from the hydraulic pump 21 is boosted to a predetermined pressure in the flow divider 22, and is then diverted to a cargo handling system and a steering system.
In the state shown in FIG. 1 in which the levers 12 and 13 are arranged at the neutral position, the hydraulic oil diverted to the cargo handling system passes through the control valves 28 and 29 provided on the hydraulic oil supply pipe 26 and thereafter. The oil is returned to the oil tank 20 through the return line 27.

When the lift lever 12 is raised in this state, the lift control valve 28 is switched to the state a, and the hydraulic oil is supplied from the hydraulic oil supply pipe 26 to the bottom chamber 4b through the pipes 26a and 30. Is done. As a result, the lift cylinder 4 is driven to extend, and the fork 8 is raised. When the lift lever 12 is lowered, the lift control valve 28 is switched to the state c, and the hydraulic oil in the bottom chamber 4b
The oil is discharged to the oil tank 20 through 0 and 27. As a result, the lift cylinder 4 is driven to contract, and the fork 8 is lowered.

When the tilt lever 13 is operated, the tilt control valve 29 is switched to state a or state c. At this time, when one of the detection switches 14 and 15 is turned on, the CPU 57 causes the solenoid drive circuit 56 to send the signal to the solenoid drive circuit 56 unless the tilt angle of the mast 3 based on the detection value of the potentiometer 18 is at a specific stop angle (forward leaning restriction angle or the like). A command value corresponding to the operation direction at the time is output. A solenoid current corresponding to the command value is output from the solenoid drive circuit 56 to the proportional solenoid valve 38, and the proportional solenoid valve 38
Opens at an opening corresponding to the current value. The pilot pressure corresponding to the opening of the proportional solenoid valve 38 is applied to the control valve 3.
7 and the pilot check valve 43, and both valves 37, 43
Opens at an opening corresponding to the pilot pressure. In this way, the opening of the control valve 37 is indirectly controlled by controlling the current value of the proportional solenoid valve 38 by the CPU 57. In addition,
When the tilt lever 13 is in the neutral position and there is no need to open the control valve 37, the detection switches 14, 1
5 are both off and no current flows through the proportional solenoid valve 38, thereby saving power consumption. When the tilt lever 13 is tilted forward, the control valve 37 is fully opened, and when the tilt lever 13 is tilted backward, the control valve 37 is opened in two stages according to the lift at that time, as described later. Is switched. When the tilt control valve 29 is switched to the state a, the operating oil in the operating oil supply pipe 26 is supplied from the branch pipe 26b to the rod chamber 9d through the pipe 36a, and the operation of the bottom chamber 9e is performed. Oil is in line 36b, 3
The oil is discharged to the oil tank 20 through 5, 27. As a result, the tilt cylinder 9 is driven to contract, and the mast 3 is tilted backward. When the tilt control valve 29 is switched to the state c, the operating oil in the operating oil supply pipe 26 is supplied from the branch pipe 26b to the bottom chamber 9e through the pipe 36b, and the rod chamber 9d Hydraulic fluid is in the line 36a,
It is discharged to the oil tank 20 through 35 and 27. As a result, the tilt cylinder 9 is driven to extend, and the mast 3 tilts forward. At this time, since the hydraulic oil is throttled by the orifice 42, the mast is tilted forward at a relatively low speed. On the other hand, the backward inclination of the mast 3 is performed at a relatively high speed with priority given to workability.

Next, various tilt-based controls performed by the CPU 57 controlling the current value of the solenoid valve 39 (that is, the proportional solenoid valve 38) will be described in order. (A) The forward leaning angle restriction control of the mast will be described.

This forward lean angle restriction control is performed by the tilt lever 1
This is executed by the CPU 57 when the front tilt detection switch 14 is turned on by operating the front tilt 3. The CPU 57 determines high lift when the lift sensor 17 is on, and low lift when off. At the time of a high lift, the forward leaning restriction angle corresponding to the detection value (load value) from the pressure sensor 19 is obtained using the map for the high lift (solid line) in FIG. Using the map for low elevation (chain line), a forward leaning restriction angle corresponding to the detection value from the pressure sensor 19 is obtained.

While the tilt lever 13 is tilted forward and the mast 3 is tilted forward, the CPU 57 monitors the tilt angle based on the detection signal from the potentiometer 18. Then, stop control is performed to stop the tilting of the mast 3 when the tilt angle reaches the previously calculated forward leaning restriction angle determined from the lift and the load at that time. That is, the current flowing through the proportional solenoid valve 38 is stopped, the control valve 37 is closed, and the mast 3 is stopped at the forward lean regulation angle. Thus, even if the operator is operating the tilt lever 13 to lean forward, the mast 3 automatically stops at the forward leaning restriction angle determined by the lift and the load at that time, and the mast 3 leans forward beyond the forward leaning restricting angle. I can't let it. Therefore, there is no possibility of instability of the vehicle, such as the rear wheels being lifted, which may occur when the mast 3 is tilted forward too much despite the high lift and heavy load.

(B) The automatic horizontal stop control of the fork will be described. This automatic horizontal stop control is performed by pressing the operation switch 16 provided on the knob 13b while holding the tilt lever 13
When the fork 8 is operated in the direction in which
This is executed by U57. Depending on the detection value of the potentiometer 18 when the tilt lever 13 is operated and which of the detection switches 14 and 15 is turned on, C
The PU 57 determines whether or not the tilt lever 13 has been operated in a direction in which the fork 8 becomes horizontal. While the mast 3 is tilted in the direction in which the tilt lever 13 is operated,
The CPU 57 monitors the tilt angle based on the detection signal from the potentiometer 18. Then, stop control is performed so that the mast 3 stops when the tilt angle reaches the horizontal set angle. In other words, the current flowing through the proportional solenoid valve 38 is stopped, the control valve 37 is closed, and the mast 3 is stopped at the horizontal set angle. By simply operating the tilt lever 13 in the direction in which the fork 8 becomes horizontal while pressing the operation switch 16, the mast 3 automatically stops when the fork 8 becomes horizontal. Therefore, even if it is difficult to grasp the attitude angle of the fork 8 from the driver's seat 10 (for example, at a high place), the fork 8 can be accurately leveled, and the subsequent work becomes easy.

(C) The backward tilting speed control of the mast will be described.
The rearward tilt speed control is executed by the CPU 57 when the tilt lever 13 is rearwardly tilted and the rearward tilt detection switch 15 is turned on. The CPU 57 determines high lift when the lift sensor 17 is on, and low lift when off. When the lift is low, the current flowing through the proportional solenoid valve 38 is represented by I
n (for example, the maximum current value), and the current value is Im (In> Im) when the height is high.

As a result, when the lift is low, the control valve 37
Is the maximum opening, and the mast 3 leans backward at the normal speed. On the other hand, when the height is high, the control valve 37 is set at the intermediate opening degree, and the mast 3 leans backward at a low speed lower than the normal speed.
Accordingly, when the vehicle is at a low lift, the vehicle is tilted backward at a normal speed, so that workability is not impaired. In addition, when the vehicle is at a high elevation, the vehicle leans backward at a speed lower than the normal speed, so that even if the load on the fork 8 is at a high position, the moving speed of the load does not become too fast, and there is no fear of load collapse. In addition, the inertia force applied to the mast 3 when tilting backward does not become excessive. Although the mast 3 is decelerated immediately before the end of the backward inclination by the impact relaxation control described later, the limitation of the backward inclination speed at the time of the high elevation also contributes to the impact relaxation at the end of the backward inclination.

(D) Mast impact mitigation control will be described.
The shock mitigation control is a control executed by the CPU 57 by interruption when the control of (A), (B), and (C) is performed.
When executing these controls, the CPU 57 calculates a deceleration start angle with respect to a stop angle in each control. For example, at the time of forward leaning, an angle on the backward tilt side of the stop angle (forward tilt restriction angle, horizontal set angle) by a predetermined angle determined from the forward tilt speed is calculated as the deceleration start angle. Also, when leaning backward, as shown in FIG. 6, the stop angle θs is an angle on the forward lean side with respect to the stop angle θs by a predetermined angle determined by the backward tilt speed corresponding to the lift at that time, that is, θ1 at low lift, and θ at high lift. θ2 is calculated as the deceleration start angle.

While the mast 3 is tilted in the direction in which the tilt lever 13 is operated, the CPU 57 monitors the tilt angle based on a detection signal from the potentiometer 18.
Then, when the tilt angle reaches the deceleration start angle, the tilting speed of the mast 3 is gradually reduced. That is, the value of the current flowing through the proportional solenoid valve 38 is closed at the stop angle (the forward tilt restriction angle in the forward tilt angle control, the horizontal set angle in the automatic horizontal stop control, and the rearward tilt angle (end angle) in the backward tilt speed control). Valve current I
Make it smaller at a constant slope so that o. When the stop control of the mast 3 is performed in this manner, the mast 3 is decelerated immediately before the stop and then stopped, so that no impact occurs at the time of the stop.

According to the first embodiment described in detail above, the following effects can be obtained. (1) In the hydraulic circuit according to the present embodiment, the tilt control valve 29 and the solenoid valve 39 are used to control the tilt system.
And are provided in series on the oil passage of the tilt cylinder 9. Therefore, even if the tilt control valve 29 sticks (sticks) due to thermal expansion of the spool and the body due to a rise in the temperature of the hydraulic oil or foreign matter in the oil entering the gap between the spool and the body, Switching can be performed by operating the tilt lever 13 with some force. Therefore, even when the tilt lever is operated, the situation in which the mast cannot be tilted due to the sticking of the valve can be less likely to occur as compared with the electric control system described in the related art.

(2) Since the lift control valve 28 and the tilt control valve 29 are the same manual switching valves as those used in the general-purpose type of mechanical control system, they are compared with those employing the electric control system. It is only necessary to add a solenoid valve 39 in series with the tilt control valve 29 on the oil passage of the tilt cylinder 9. Therefore, the hydraulic circuit configuration can be simplified, and design changes can be reduced. In the case of speed control in the electric control system, an electromagnetic valve for flow rate control is separately required in addition to the electromagnetic switching valve.
Since the stop control and the speed control are performed by the individual solenoid valves 39, the number of solenoid valves used can be smaller than that of the electric control system. Therefore, the configuration of the hydraulic circuit and the control system can be simplified, and power consumption can be reduced by reducing the number of solenoid valves. In addition, parts normally used in the mechanical control system including the control valves 28 and 29 can be used.

(3) Control valve 37 and proportional solenoid valve 38
Since the electromagnetic valve 39, which is one electromagnetic proportional control valve composed of the following, is used, two types of control, that is, the stop control of the mast 3 and the speed control can be performed with only one electromagnetic valve 39.

(4) Since the control valve 37 is driven by the pilot pressure and the proportional solenoid valve 38 is used to control the pilot pressure, the solenoid valve is compared with a configuration using a direct-acting solenoid valve. The solenoid current for driving the drive 39 can be reduced with a small current. Therefore, the power consumption of the solenoid valve 39 can be reduced.

(5) Since the proportional solenoid valve 38 is a normally closed valve, current can be supplied only when the tilt lever 13 is operated, so that power consumption can be reduced.

(6) The fork 8 and the weight of the load, etc., originally act on the mast 3 to force it to lean forward, and the mast 3 is connected to the rod chamber 9d to which a compression pressure is applied by the weight of the mast 3 falling forward. An electromagnetic valve 39 (that is, the control valve 37) is provided on the conduit 36a. Therefore, since the mast 3 is tilted forward by removing the hydraulic oil to which the compression pressure due to the weight of the mast 3 is applied, the positional accuracy when the mast 3 is stopped at a predetermined stop angle is easily obtained. That is, it is possible to stop the mast 3 at the forward lean restriction angle or the horizontal set angle with high positional accuracy.

(7) As one of the controls for stopping the mast 3 by controlling the solenoid valve 39, the forward inclination restricting control for restricting the forward inclination of the mast 3 according to the lift and the load is performed. It is possible to avoid an unstable state such as the rear wheel being lifted.

(8) As one of the stop controls of the mast 3 by controlling the solenoid valve 39, an automatic horizontal stop control for stopping the fork 8 horizontally when the operator operates the tilt lever 13 while pressing the operation switch 16 Is performed, the fork 8 can be accurately leveled even at a position where it is difficult to grasp the attitude angle, and subsequent work can be easily performed.

(9) As one of the speed controls of the mast 3 by controlling the solenoid valve 39, the rear tilt speed control for limiting the rear tilt speed of the mast 3 when the lift is high is performed.
It is possible to move the load on the fork 8 at an appropriate speed without causing the load to collapse regardless of the height. In addition, the inertia force applied to the mast 3 at the time of tilting backward at high elevation does not become excessive,
It also contributes to cushioning at the end of the backward tilt.

(10) As one of the speed controls of the mast 3 by controlling the solenoid valve 39, the shock mitigation control for decelerating the mast 3 just before the stop angle is performed. Can be eased. That is,
The impact when the mast 3 stops at the forward lean restriction angle, the horizontal set angle, and the backward lean end angle can be reduced. In particular, in consideration of workability, the mast 3 has a remarkable effect in alleviating an impact at the time of stopping when the mast 3 is tilted rearward relatively fast.

(11) On the pipe line 36a connected to the rod chamber 9d which receives the compressive pressure due to the weight acting on the forwardly inclined side of the mast 3, the pilot reversely moves to a position closer to the tilt cylinder 9 than the solenoid valve 39 (that is, the control valve 37). Since the stop valve 43 is provided, it is possible to reduce a natural forward lean amount of the mast 3 at the time of key-off.

(12) When the key is turned off, the solenoid valve 39, which is a normally closed valve, and the pilot check valve 43 are connected to the line 36.
Since a is cut off, it is possible to prevent the mast 3 from leaning forward even if a third person accidentally operates the tilt lever 13 at the time of key-off. In addition, even if one of these valves 39 and 43 fails, this purpose is achieved.

(13) Bottom chamber 4a of lift cylinder 4
The pilot check valve 34 is provided on the pipe 30 connecting the lift control valve 28 and the lift control valve 28, thereby preventing the fork 8 from lowering even if a third party accidentally operates the lift lever 12 at the time of key-off. it can. Also, fork 8 at key-off
Natural descent can be prevented.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, an electromagnetic valve provided in series with the tilt control valve is
It comprises a control valve capable of switching the oil passage of the tilt cylinder to a plurality of stages of opening, and a plurality of on / off valves in which a pilot pressure for operating the control valve can be switched to a plurality of stages. . That is, since the opening degree of the solenoid valve required for the control of the tilt system is in three stages of full closing, half opening, and full opening (however, when the deceleration control with a constant inclination in the shock relaxation control is not performed), the pilot pressure is reduced. Instead of using a proportional solenoid as a control valve, a plurality of on / off valves are used in which pilot pressures can be switched in three necessary steps. Note that, in the present embodiment, a description will be given mainly of points different from the configuration of the first embodiment, and the same or corresponding components as those of the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

FIG. 7 shows a hydraulic circuit in this embodiment. Also in this embodiment, a lift including a manual switching valve is provided on a hydraulic oil supply pipe 26 which is piped so as to return the hydraulic oil discharged from the hydraulic pump 21 and divided by the flow divider 22 to the return pipe 27. The control valve 70 for tilt and the control valve 29 for tilt are provided in series. In this embodiment, the lift control valve 70 comprises a 9-port 3-position switching valve.

An oil passage for operating the tilt cylinder 9 is composed of a branch conduit 26b, conduits 36a and 36b, a discharge conduit 35, and the like. When the tilt control valve 29 is switched to one of the states a and b, the hydraulic oil from the branch line 26b flows through one of the lines 36a and 36b and is sent to one chamber 9d (9e) of the tilt cylinder 9. And other rooms 9e
The hydraulic oil discharged from (9d) passes through one of the pipes 36a and 36b which is not the side used for supply, and the discharge pipe 3
5. The oil is discharged to the oil tank 20 through the return line 27. The solenoid valve 71 is connected to the pipe 36a connected to the rod chamber 9d.
It is provided above. The solenoid valve 71 includes a control valve 72 capable of opening and closing its flow path on a pipe 36a, and two control valves for switching a pilot pressure for operating the control valve 72 stepwise (three steps in the present embodiment). (Two-position switching valve) 73, 74.

The control valve 72 has two switching valves 75 and 76 built in, and can be switched to a three-stage opening degree of full closing, half opening and full opening by a combination of switching positions of the switching valves 75 and 76. It is a valve. That is, the control valve 72 is configured such that the first switching valve 75
State, when the second switching valve 76 is in the b state, it is fully closed, when the first switching valve 75 is in the b state, when the second switching valve 76 is in the b state, it is half open, and when the first switching valve 75 is in the b state, It is fully opened when the second switching valve 76 is in the state a.

On the other hand, the two on / off valves 73 and 74 are respectively connected to pipes 77 for transmitting the discharge pressure of the hydraulic pump 21. The first on / off valve 73 is connected to the first switching valve 75 via a conduit 78, and controls a pilot pressure for operating the first switching valve 75. The second on / off valve 74 is connected to the second switching valve 76 by a pipe line 79, and controls a pilot pressure for operating the second switching valve 76. The first on / off valve 73 is a normally open valve, and outputs the discharge pressure (pilot pressure) of the hydraulic pump 21 to the first switching valve 75 in the state a (off state) and connects the line 78 in the state b (on state). Line 8 leading to return line 27
Connect to 0. The second on / off valve 74 is a normally closed valve. The second on / off valve 74 connects the line 79 to the line 81 connected to the return line 27 in the state a (off state), and discharges the hydraulic pump 21 in the state b (on state). The pressure (pilot pressure) is output to the second switching valve 76.

A pilot check valve 82 for reducing the natural forward tilt amount of the tilt cylinder 9 at the time of key-off (engine stop) is provided on the pipe line 36a closer to the tilt cylinder 9 than the control valve 72. ing. Switching valve 8 operated by the output pilot pressure of first on / off valve 73
3 switches the pilot pressure for operating the pilot check valve 82.

Further, a pilot check valve 84 as a second pilot check valve for preventing the lift cylinder 4 from lowering naturally at the time of key-off (engine stop) is provided on the pipeline 30. The switching valve 8 that operates using the discharge pressure of the hydraulic pump 21 transmitted through the pipe line 85 as a pilot pressure
6 switches the pilot pressure for operating the pilot check valve 84. The pilot check valve 84 also has a function of preventing the fork 8 from lowering even if a third party erroneously operates the lift lever 12 at the time of key-off.

Further, a relief valve 88 is provided on a pipe 87 connecting the pipe 23 and the return pipe 27. When the tilt control valve 29 or the lift control valve 70 is switched to a state in which the flow path of the hydraulic oil supply pipe 26 is shut off, the relief valve 88 does not have an upstream hydraulic pressure exceeding the set pressure. In order to allow the hydraulic oil to escape.
The filters 89 and 90 are for removing foreign substances in oil.

The controller 53 has basically the same configuration as that of the first embodiment, and the CPU 57 controls on / off of the current flowing to the two on / off valves 73 and 74 via the solenoid drive circuit 56. For a predetermined time (about 1 to 2 seconds) immediately after key-on (engine start), each pilot check valve 8
In order to open the valves 2 and 84, the on / off valves 73 and 74 are forcibly held in the off state even when the tilt lever 13 is operated. In this embodiment, the first
Of the various controls by the CPU 57 performed in the embodiment, only the shock mitigation control is not performed.

This hydraulic circuit operates as follows. When the key is turned off (the engine is stopped), the on / off valves 73 and 74 are both in the off (demagnetized) state. The switching valves 83 and 86 are both in the a state, and the pilot check valves 82 and 84 are held closed by the hydraulic pressure of the chambers 9d and 4b. In addition, the control valve 72 is the same as the control valve 72 shown in FIG.
It is in the state of.

In this state, when the hydraulic pump 21 is driven by key-on (engine start), the first on-off valve 73
Is in a valve-open state in which the pipes 77 and 78 communicate with each other, the discharge pressure is transmitted through the pipes 77 and 78, the switching valve 83 is switched from the a state to the b state, and the discharge pressure is transmitted through the pipe 85. Thus, the switching valve 86 switches from the state a to the state b. As a result, the hydraulic pressure applied to the pilot check valves 82 and 84 from the respective chambers 9d and 4b disappears, and the pilot check valves 82 and 84 are opened and held. The discharge pressure is also applied to the first switching valve 75, and the control valve 72
5 and 76 are fully opened with both valves opened.

[0096] Among the controls performed in the first embodiment,
In order to perform other controls other than the shock mitigation control, it is necessary to switch the opening of the control valve 72 to three stages of fully closed, half opened, and fully opened. That is, in order to perform the stop control in the forward inclination restriction control and the automatic horizontal stop control, the opening of the control valve 72 needs to be fully closed. In addition, in order to perform speed control in the backward tilt speed control, the opening of the control valve 72 needs to be half-opened or fully opened in accordance with the lift at that time. In this embodiment, the three-stage switching of the opening of the electromagnetic valve 71 is performed using the control valve 72 and two on / off valves 73 and 74.

Normally, both the on-off valves 73 and 74 are turned off, and the control valve 72 is kept in the fully open state. Mast 3
The CPU 57 controls the on / off valves 73 and 7 only when the control valve 72 is fully closed to stop the control valve 72 by the stop control and when the control valve 72 is half-opened by the backward tilting operation at a high elevation of the mast 3.
4 is turned on.

That is, in order to stop the mast 3 at a predetermined stop angle in the forward inclination control and the automatic horizontal stop control,
When fully closing the control valve 72, the CPU 57 turns on the first on / off valve 73 and turns on the second on / off valve 74. As a result, the first on / off valve 73 is switched from the state a to the state b, and the conduits 78 and 80 communicate with each other.
Since the discharge pressure applied to the switching valve 75 disappears, the first switching valve 75 closes. At the same time, the second on / off valve 74 is switched to the state b, the conduits 77 and 79 communicate, and the second switching valve 76 is closed by the discharge pressure. Thus, the control valve 72 is fully closed. At this time, the switching valve 83
, The pilot check valve 82 is closed, but there is no problem since the control valve 72 is fully closed.

When the control valve 72 is half-opened at the time of high elevation in the backward inclination speed control, the CPU 57 turns the first on / off valve 73 off and the second on / off valve 74 on. As a result, the first on / off valve 73 is switched to the state a, whereby the first switching valve 75 is opened. At the same time, the second on / off valve 74 is switched from the state a to the state b, and the second switching valve 76 is closed. Thus, the control valve 72 is in a half-open state.

In this embodiment, the electromagnetic valve 71 including the control valve 72 and the two on / off valves 73 and 74 is used, so that the electromagnetic valve 71 provided in the tilt-type oil passage can be opened in three steps. Was controlled. By using the on / off valves 73 and 74, the pressure reducing valve 33 and the proportional solenoid valve 38 required in the first embodiment are not required, and the hydraulic circuit can be simplified. Further, since the on / off control is performed, the control by the CPU 57 can be simplified. Further, in the electric control system described in the related art, when the electric control system fails, the mast cannot be moved even by operating the tilt lever. On the other hand, even if the electric control system for controlling the solenoid valve 71 breaks down and the on / off valves 73 and 74 are not turned on, since the control valve 72 is in the fully open state at this time, the tilt lever 13 is operated. By switching the tilt control valve 29, the mast 3 can be tilted by a mechanical control method. In addition, the deceleration for reducing the impact is not performed at the end of the backward inclination, but the impact at the end of the backward inclination is reduced to some extent because the backward inclination speed of the mast 3 is limited at the time of high elevation. In addition, according to this embodiment, among (1) to (13) described in the first embodiment, (1) the effect of easily avoiding the situation where the mast cannot tilt due to the sticking of the valve, (2) Simplification of the hydraulic circuit configuration by adding a solenoid valve to the manual switching valve, power saving by reducing the number of solenoid valves, the effect that parts used in the machine control method can be used, (3) one solenoid valve 71 Therefore, two kinds of controllable effects of stop control and speed control of the mast 3 are provided. (4) The electromagnetic valve 71 is controlled by using the on / off valves 73 and 74 to adjust the pilot pressure for controlling the control valve 72. (6) The effect of improving the stop position accuracy of the mast 3 by providing the solenoid valve 71 (control valve 72) on the pipe 36a connected to the rod chamber 9d, (7) The forward tilt angle control Vehicle anxiety such as the rear wheel being lifted Avoidance effect, (8) effect of accurately leveling the fork 8 by automatic level stop control, (9) effect of restricting the rearward tilting speed of the mast 3 according to the lift by rearward tilting speed control, (11) reverse pilot The effect of reducing the natural forward lean amount of the mast 3 at the time of key-off by the stop valve 82, (1
2) The effect of preventing the mast 3 from tilting forward by the pilot check valve 82 even if a third person erroneously operates the tilt lever 13 at the time of key-off. Even if the lift lever 12 is operated, the effect of preventing the fork 8 from lowering and the effect of reducing the natural lowering of the fork 8 at the time of key-off can be similarly obtained.

The present invention is not limited to the above embodiments, but may be implemented as follows, for example, without departing from the spirit of the invention. (N) In each of the above embodiments, the lift is monitored only in two stages of the high lift and the low lift by the lift sensor 17 composed of the proximity switch. However, the lift is continuously detected and the mast 3 is detected.
It is also possible to adopt a configuration in which the forward lean restriction angle and the backward lean speed are continuously changed according to the continuous change of the lift. For example, as shown in FIG. 8, a lift sensor 92 that detects the rotation of the reel 91 is used. The reel 91 is urged in a direction in which a wire connected to the fork 8 or the inner mast 3b can be wound, and a height sensor 92 detects a winding amount of the reel 91 and continuously detects a height. . Then, for example, a map as shown in FIG. 9 for obtaining the backward tilt speed according to the lift is prepared in a ROM or the like. In this map, a rearward tilting speed (maximum rearward tilting speed) VH corresponding to the full opening of the solenoid valve is set in a low lifting height range below a predetermined lifting height Ho, and a rearward tilting speed V in a high lifting range above the lifting height Ho. Decreases continuously as the lift increases (that is, the opening of the solenoid valve is continuously narrowed),
The rearward tilting speed (minimum rearward tilting speed) VL is set at the maximum lift Hmax. By continuously changing the current value of the proportional solenoid valve 38 according to the lift based on this map, the backward tilting speed of the mast 3 can be set more finely according to the lift. In addition, the map of the forward lean restriction angle is set so as to continuously change with respect to both the lift and the load, and the lift value continuously detected by the lift sensor 92 and the lift value continuously detected by the pressure sensor 19 are set. It is also possible to adopt a configuration in which the forward lean regulation angle is more finely controlled based on the applied load value. It should be noted that the present invention is not limited to the height sensor 92, and may be implemented using another sensor capable of continuously detecting the height.

(M) In the first embodiment, the solenoid valve 39
May be a normally open valve, and a current may be supplied only during stop control (fully closed), when the backward tilt speed is limited (half open), and during shock mitigation control. According to this configuration, the first
The power consumption of the proportional solenoid valve 38 can be further reduced as compared with the configuration of the embodiment. If the solenoid valve 39 is a normally open valve, as described in the second embodiment,
Even when the electric control system breaks down, the mast 3 can be tilted by operating the tilt lever 13 in the same manner as in the mechanical control system.

(G) In the first embodiment, the pilot check valve 43 may be omitted. In this configuration as well, although the effect of reducing the natural forward inclination of the mast 3 is somewhat inferior, the oil passage (pipe 36a) is shut off by the solenoid valve 39, which is a normally closed valve. Even if the lever 13 is operated, the mast 3 does not tilt forward. Further, in the configuration in which the pilot check valve 82 of the second embodiment is omitted, the on / off valve 7
The solenoid valve 71 is configured as a normally closed valve in which the control valve 72 is fully closed when both 3 and 74 are off, and the mast 3 does not tilt forward even if a third party operates the tilt lever 13 during key-off. You may do so.

(H) The position of the solenoid valve provided in series with the manual switching valve on the oil passage is not limited to the above embodiment. As long as it is on a tilt-type oil path, it may be on the pipe 36b, or may be provided on the pipe 26b or the pipe 35. In other words, when the manual switching valve is switched to the valve opening position, the position at which the flow rate of the hydraulic oil flowing through the oil passage of the hydraulic cylinder (however, the portion that does not also serve as the oil passage of another cylinder) can be adjusted (including shut-off). If so, it can be changed as appropriate.

(J) In each of the above embodiments, the solenoid valve is formed from a control valve provided on the oil passage of the hydraulic cylinder and a proportional solenoid valve or an on / off valve for adjusting a pilot pressure for operating the control valve. Although configured, a direct-acting solenoid valve that directly drives a spool that opens and closes an oil passage by a solenoid may be employed. According to this configuration, although power consumption for driving the solenoid valve is increased, a pipe line and a pressure reducing valve for pilot control can be eliminated.

(K) The deceleration method in the shock mitigation control is as follows.
The method is not limited to the method of decelerating to the stop angle at a constant inclination (deceleration). For example, a method may be adopted in which the mast tilting speed is sufficiently reduced just before the stop angle, and the mast is stopped at a very slow speed (constant speed).

(P) In each of the above embodiments, the solenoid valve having the functions of a flow control valve and an open / close valve capable of continuously or stepwise changing the opening so that stop control and speed control can be performed by one valve. 39, 71 were adopted. On the other hand, an on-off valve (for example, an on-off valve) having no flow rate adjusting function may be employed as the electromagnetic valve, and only the stop control of the cargo handling equipment may be performed. Alternatively, a flow control valve having no fully closed function may be adopted as the electromagnetic valve, and only the speed control of the cargo handling equipment may be performed. According to these configurations, the size of the solenoid valve can be easily reduced, and the control can be further simplified.

(Q) In the above embodiment, the automatic horizontal stop control, the forward tilt angle control, the backward tilt speed control, and the shock mitigation control are adopted as the mast tilt control. However, the manual switching valve and the solenoid valve are combined. With the hydraulic circuit configuration described above, other stop control and speed control such as rearward tilt angle control can be adopted. Further, some (at least one) of all the controls in the above embodiment may be selected and adopted.

(S) In the above embodiment, the rearward tilting speed of the mast is changed according to the lift. However, the rearward tilting speed of the mast may be determined based on both the vertical and the load. That is, the backward inclination speed is determined using a map or the like using the respective detected values from the elevation sensor and the pressure sensor. The map is set such that the higher the lift and the heavier the load, the slower the mast backward tilt speed becomes, by taking into account the inertial force of the load at the time of backward leaning that varies with the lift and load. According to this configuration, it is possible to prevent the inertial force of the load when the mast is tilted backward from becoming excessive. Further, it is possible to more effectively suppress the impact at the time of the backward inclination end of the mast.

(T) In each of the above embodiments, the mast tilt control is performed by providing the solenoid valve in series with the manual switching valve on the oil passage of the tilt cylinder 9, but this configuration is applied to other hydraulic cylinders. May be applied to control the cargo handling equipment in the industrial vehicle. For example, in a forklift, the control of the lift cylinder 4 may be embodied. That is, an electromagnetic valve is provided on the conduit 30 connecting the lift control valve 28 (70) and the lift cylinder 4, and by controlling the opening of the electromagnetic valve, the stop control of the fork 8 and the elevating speed control are performed. You may. For example, the present invention may be applied to automatic lifting control for automatically lifting a fork to a preset height. Of course, the present invention may be applied to a reach cylinder of a reach type forklift or a side cylinder for moving a fork in the vehicle width direction.

(V) The detected value for determining the forward leaning regulation angle in the forward leaning regulation control is not limited to the lift and the load.
The detection value is not particularly limited as long as the detection value can detect an unstable state of the vehicle due to the movement of the center of gravity of the vehicle in the front-rear direction. For example, by detecting the vehicle body posture by an inclination angle sensor, for example, on a downward slope road surface, the forward inclination restriction angle is set to be smaller than that on a flat road surface,
It is also possible to adopt a control method in which the forward inclination restriction angle is set to be larger on an upwardly inclined road surface than on a flat road surface.

(W) In the above embodiment, the industrial vehicle is embodied in a forklift, but may be applied to other industrial vehicles. For example, the present invention may be applied to a construction machine such as a power shovel or an aerial work vehicle.

The technical ideas (inventions) other than the claimed invention, which have been grasped from the above embodiments, will be described below together with their effects. (A) In claim 1, the solenoid valve is a solenoid on-off valve. According to this configuration, since the electromagnetic valve is an electromagnetic on-off valve, stop control of the cargo handling equipment can be performed.

(B) In claim 1, the solenoid valve is
It is an electromagnetic flow control valve. According to this configuration, since the electromagnetic valve is an electromagnetic flow control valve, speed control of the cargo handling equipment becomes possible.

(C) Claims 1 to 9 and Claims 11 to 11
14. The solenoid valve according to claim 13, wherein the solenoid valve is a normally open valve. According to this configuration, even if the electric control system for controlling the electromagnetic valve fails, the hydraulic cylinder can be operated and the cargo handling equipment can be operated by operating the operation unit similarly to the mechanical control method. (D) The vehicle state detection means according to claim 5, wherein the detection means is an inclination angle detector for detecting an inclination angle of the mast, and detects an unstable state due to a movement of the center of gravity of the vehicle in the front-rear direction. And a forward leaning restriction angle calculating means for obtaining a forward leaning restricting angle of a mast that can stably hold the vehicle using a value detected by the vehicle state detecting means, wherein the control means comprises the tilt angle detector And a mast forward-inclination restricting means for controlling the solenoid valve so that the mast stops at the forward-inclination restricting angle based on the detection value from the controller. According to this configuration, the forward lean restriction angle of the mast is calculated by the forward lean restriction angle calculating means from the detection value from the vehicle state detecting means. The operation unit is operated,
When the mast is tilted forward, the solenoid valve is controlled based on the detection value from the tilt angle detector so that the mast stops at the forward tilt restriction angle. Therefore, even if you continue to operate the operation unit,
The mast can be stopped at a forward leaning restriction angle capable of maintaining the vehicle in a stable state.

(E) In the above (d), the vehicle state detecting means includes a lift detector for detecting a lift of the cargo handling equipment and a load detector for detecting a load on the cargo handling equipment. The forward leaning restriction angle calculating means is set so as to obtain the mast forward leaning restricting angle using the detected values of the lift and the load. According to this configuration, since the mast's forward inclination regulating angle is determined from the lift detected by the lift detector and the load on the cargo handling equipment detected by the load detector, the vehicle is determined by the lift and the load. The forward inclination of the mast can be regulated by the inclination angle corresponding to the unstable state in the front-rear direction. The vehicle state detecting means includes a lift sensor 17 as a lift detector,
92, a pressure sensor 19 as a load detector, and a controller 53.

(F) In claim 8, the stop angle is:
This is the forward leaning restriction angle in (D) or (E). According to this configuration, the impact when the mast stops at the forward leaning restriction angle can be reduced.

(G) In claim 13, the hydraulic cylinder is for tilting a mast for supporting the cargo-handling equipment so as to be able to move up and down, and the solenoid valve is configured to load the mast in the hydraulic cylinder when the mast is tilted forward. It is provided on an oil passage connected to the chamber on the pressure receiving side. According to this configuration, the hydraulic fluid in the chamber to which the solenoid valve is connected is pushed out while receiving the load pressure when the mast is tilted forward, so that the mast is tilted forward. Position accuracy is easy to achieve.

[0119]

As described in detail above, according to the first aspect of the present invention, since a solenoid valve is added to the hydraulic passage of the hydraulic cylinder in addition to the manual switching valve, the stop control and speed of the cargo handling equipment can be controlled. The hydraulic circuit for controlling can be configured relatively easily, and it is easy to avoid inoperability of the cargo handling equipment due to sticking.

According to the second aspect of the present invention, since the electromagnetic valve is an electromagnetic proportional control valve, the opening and closing of the oil passage of the hydraulic cylinder and the flow rate adjustment can be performed by one electromagnetic valve. Claim 3
According to the invention described in (1), since the proportional solenoid valve is used for adjusting the pilot pressure for operating the control valve provided in the oil passage of the hydraulic cylinder, the power consumption for driving the solenoid valve can be reduced.

According to the fourth aspect of the invention, the control valve can be adjusted to the required opening stepwise with a simple configuration of a combination of a plurality of on / off valves, and the hydraulic circuit configuration can be further simplified. it can.

According to the fifth aspect of the present invention, the hydraulic cylinder is for tilting the mast for supporting the loading / unloading equipment so as to be able to move up and down.
Tilt speed control or both controls can be performed.

According to the sixth aspect of the present invention, the automatic horizontal stop control is employed as one of the stop controls of the cargo handling equipment by the solenoid valve, so that the operation unit is continuously operated with the operation switch being operated. Thus, the cargo handling equipment can be automatically stopped horizontally.

According to the seventh aspect of the present invention, the rearward tilting speed control is employed as one of the speed control of the cargo handling equipment by the solenoid valve, so that the rearward tilting speed of the mast is adjusted according to the lift at that time. The higher the height, the slower it can be limited.

According to the eighth aspect of the present invention, as one of the speed control of the cargo handling equipment by the electromagnetic valve, the shock mitigation control is employed, so that the mast is decelerated just before the stop and the shock at the stop is reduced. be able to.

According to the ninth aspect of the present invention, the shock mitigation control is employed in at least one of the automatic horizontal stop control and the backward tilting operation. Therefore, when the cargo handling equipment stops in the horizontal posture in the automatic horizontal stop control. It is possible to reduce the impact and the impact at the time of completion of the backward tilt of the mast.

According to the tenth aspect of the present invention, since the solenoid valve is a normally closed valve, even if a third party operates the operation unit at the time of key-off to switch the manual switching valve to the open state, cargo handling equipment can be used. Can be prevented from moving due to its weight or the like.

According to the eleventh aspect of the present invention, the pilot check valve is provided on the oil passage closer to the hydraulic cylinder than the solenoid valve, so that the natural lowering and natural leaning of the cargo handling equipment at the time of key-off can be more reliably prevented. it can. Further, when the solenoid valve is a normally open valve, it is possible to prevent the cargo handling equipment from lowering or leaning forward even if a third party erroneously operates the operation unit to open the manual switching valve when the key is turned off.

According to the twelfth aspect of the present invention, since the second pilot check valve is provided on the oil passage of the second hydraulic cylinder between the second manual switching valve and the second manual switching valve, a third party can erroneously make the key-off operation. Even if the second manual switching valve is opened by operating the operation unit, it is possible to prevent the cargo handling equipment from moving due to its own weight or the like.

According to the thirteenth aspect, the solenoid valve is provided on the oil passage connected to the chamber on the side receiving the load pressure from the cargo handling equipment in the hydraulic cylinder, and the hydraulic oil in the chamber to which the solenoid valve is connected is provided. Is pushed out while receiving the load pressure from the cargo handling equipment, so that the positional accuracy is easily obtained when the stop control of the cargo handling equipment is performed. For example, if the hydraulic cylinder is for tilting the mast, the mast can be accurately stopped at a predetermined stop angle.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a forklift according to a first embodiment.

FIG. 2 is an electric circuit block diagram of a forklift.

FIG. 3 is a side view of a tilt lever.

FIG. 4 is a side view of the forklift.

FIG. 5 is a diagram showing a map for forward lean angle restriction control.

FIG. 6 is a diagram showing a map for rearward tilt speed control and impact relaxation control.

FIG. 7 is a hydraulic circuit diagram of a forklift according to a second embodiment.

FIG. 8 is a partial side view of a forklift including a lift sensor according to another example.

FIG. 9 is a diagram showing a map for controlling the backward inclination speed in the same manner.

[Explanation of symbols]

1: Forklift as an industrial vehicle, 3: Mast, 4
... lift cylinder as second hydraulic cylinder, 8 fork as cargo handling equipment, 9 ... tilt cylinder as hydraulic cylinder, 9a ... piston rod, 9d ... rod chamber as chamber, 12 ... lift lever, 13 ... operation unit , A forward tilt detection switch that constitutes operation detection means, 15 a rear inclination detection switch that constitutes detection means and operation detection means, and a rear inclination detection detector, 16 operation switches, and 17 detection means And a height sensor as a height detector, 18... A potentiometer as a tilt angle detector and 21... A hydraulic pump, 26 b, 36 a, 36 b and 3.
5: Pipe line as oil passage, 28, 70 ... Lift control valve as second manual switching valve, 29 ... Tilt control valve as manual switching valve, 34, 84 ... Pilot as second pilot check valve Check valve, 39: solenoid valve as an electromagnetic proportional control valve, 37: control valve constituting an electromagnetic valve, 38: proportional solenoid valve constituting an electromagnetic valve, 43, 82: pilot check valve, 53: control means, A controller as an automatic horizontal stop means, a backward tilt speed control means and an impact relaxation control means,
71: solenoid valve, 72: control valve constituting the solenoid valve, 73,
74 ON / OFF valve constituting the solenoid valve.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makio Tsukada 1671 Asano, Toyono-cho, Kamiminochi-gun, Nagano Prefecture Nishina Kogyo Co., Ltd. (72) Inventor Shigeto Nakashima 1671, Asano, Toyono-cho, Kamiminochi-gun, Nagano Nika Kogyo

Claims (13)

[Claims] 1. A manual switching valve that is switched by operating an operation unit for operating a cargo handling device, a hydraulic cylinder for driving the cargo handling device, and the manual switching on an oil passage of the hydraulic cylinder. A solenoid valve provided in series with the valve, a detection unit for obtaining a detection value necessary for controlling the cargo handling equipment, and a control unit for controlling the solenoid valve based on the detection value obtained from the detection unit A hydraulic control device for an industrial vehicle, comprising: 2. The hydraulic control device for an industrial vehicle according to claim 1, wherein the electromagnetic valve is an electromagnetic proportional control valve. 3. The control valve according to claim 1, wherein the electromagnetic proportional control valve is provided in series with the manual switching valve on an oil passage of the hydraulic cylinder, and a proportional solenoid for adjusting a pilot pressure required to drive the control valve. 3. The hydraulic control device for an industrial vehicle according to claim 2, comprising a valve. 4. The electromagnetic valve, comprising: a control valve capable of switching to a plurality of openings; and a plurality of pilot valves which are capable of selecting a pilot pressure necessary for switching the control valve to a plurality of openings in a stepwise manner. The hydraulic control device for an industrial vehicle according to claim 1, further comprising an on / off valve. 5. The hydraulic control device for an industrial vehicle according to claim 1, wherein the hydraulic cylinder is for tilting a mast that supports the cargo handling equipment so as to be able to move up and down. . 6. The detecting means includes an operation switch operated when the cargo handling equipment is automatically stopped horizontally, and an inclination angle detector for detecting an inclination angle of the mast. When inputting a signal indicating that the operation switch has been operated, the solenoid valve is closed such that the mast stops at a horizontal setting angle for leveling the cargo handling equipment based on a detection value from the tilt angle detector. 6. The hydraulic control device for an industrial vehicle according to claim 5, further comprising an automatic horizontal stop means for performing stop control for causing the automatic horizontal stop. 7. The control means includes a lift detector for detecting a lift of the cargo handling equipment, and a backward tilt operation detector for detecting that the operation unit is tilted backward. The means is configured such that, when a detection signal indicating that the operation section is operated to perform the backward tilt operation is input from the backward tilt operation detector, the mast is configured to have at least two or more backward tilt speeds that are slower as the lift is higher. A rearward tilting speed control means for determining a rearward tilting speed according to the height at that time based on a detection value from the height detector and adjusting the opening of the solenoid valve to an opening corresponding to the rearward tilting speed. The hydraulic control device for an industrial vehicle according to claim 5, further comprising: 8. The detection means includes an inclination angle detector for detecting an inclination angle of the mast, and the control means determines an inclination angle of the mast based on a detection value from the inclination angle detector. 6. The shock mitigation control means according to claim 5, further comprising: an impact mitigation control unit that adjusts the opening of the solenoid valve to reduce the tilting speed of the mast when the vehicle reaches a deceleration range set before the stop angle. Hydraulic control device for industrial vehicles. 9. The hydraulic control device for an industrial vehicle according to claim 8, wherein the stop angle is at least one of the horizontal setting angle and the rearward tilt restriction angle of the mast. 10. The electromagnetic valve is a normally closed valve, comprising an operation detecting means for detecting that the operation section has been operated, and wherein the control means receives the detection signal from the operation detecting means and receives the electromagnetic signal. The hydraulic control device for an industrial vehicle according to any one of claims 1 to 9, wherein the valve is opened at times other than the predetermined valve closing timing. 11. A pilot check valve operated by hydraulic pressure from a hydraulic pump driven by starting of a vehicle is provided on an oil passage connecting the manual switching valve and the hydraulic cylinder, the hydraulic cylinder being driven by the weight of the cargo handling equipment. The hydraulic control device for an industrial vehicle according to any one of claims 1 to 10, wherein the hydraulic control device is provided closer to the hydraulic cylinder than the electromagnetic valve in a direction in which the displacement of the piston rod can be prevented. 12. A vehicle comprising a plurality of hydraulic cylinders for cargo handling,
The second hydraulic cylinder and a second manual switching valve for opening and closing the oil passage of the second hydraulic cylinder are provided on an oil passage of a second hydraulic cylinder which does not include the solenoid valve on the oil passage of the plurality of hydraulic cylinders. A second pilot check valve operated by hydraulic pressure from a hydraulic pump driven by starting of the vehicle,
The hydraulic control device for an industrial vehicle according to any one of claims 1 to 11, wherein the hydraulic control device is provided in a direction capable of preventing displacement of a piston rod of the second hydraulic cylinder due to the weight of the cargo handling equipment. 13. The apparatus according to claim 1, wherein the solenoid valve is provided on an oil passage connected to a chamber of the hydraulic cylinder that receives a load pressure from the cargo handling equipment. The hydraulic control device for an industrial vehicle according to the above.