JPH11292495A - Hydraulic controller for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic controller for industrial vehicles capable of simply releasing an attachment of an industrial vehicle in a locked condition and reducing manufacturing cost of the industrial vehicle for the manufacturing control becoming easy. SOLUTION: An operating lever 14 is supported by a supporting arm 16 in a rotationally movable manner with respect to the supporting arm 16. One of the ends of a wire 17 having the other end connected to a lever side wire fixing member 14a fixed to the operating lever 14 is connected to a link mechanism 19 for releasing a needle valve 18 acting as a lock releasing opening and closing valve. The link mechanism 19 is composed of a supporting member 22 fixed to a valve element 18a of the needle valve 18 and a lever 23 connected to the supporting member 22 in a rotationally movable manner with respect to the supporting member 2. The needle valve 18 functioning as a lock releasing opening/closing valve is connected to a specific position in the intermediate of the lever 23 by a bolt 26 functioning as a detachable connecting means. The needle valve 18 is provided with the valve element 18a, a valve stem 18d and a spring 18e for energizing and retaining the valve stem 18d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil control valve, and more particularly to a hydraulic control device for an industrial vehicle.

[0002]

2. Description of the Related Art In a forklift, a fork is lifted and lowered together with a lift bracket by a mast provided with an out mast and an inner mast provided at a front portion of a vehicle. The mast is expanded and contracted by the operation of the lift cylinder,
It is tilted by the operation of the tilt cylinder. The operation of the lift cylinder or the tilt cylinder is performed by manual operation of a lift control valve or a tilt control valve that controls switching between supply and discharge of hydraulic oil to and from the lift cylinder and the tilt cylinder, respectively.

FIG. 10 shows a hydraulic circuit for raising and lowering a fork in a conventional hydraulic control device for a forklift. As shown in FIG. 10, the lift cylinder 40 of the forklift is controlled to expand and contract by switching the lift control valve 41. Lift control valve 41
Is manually operated by the lift lever 42. When the lift lever 42 is operated to the raised position, the lift control valve 41 connects the pipe 44 to the pipe 43 and the lift lever 42
Is operated to the lowered position, the return line 45 and the line 43 are communicated. When the lift lever 42 is operated to the neutral position, the lift control valve 41 shuts off the pipe 43 from the pipe 44 and the return pipe 45, and holds the piston rod 40b at a predetermined position. .

[0004] However, the lowering operation of the fork by the lift cylinder 40 is performed by lowering the piston rod 40b by the weight of the fork and the mast. Therefore, in the conventional apparatus, when the lift lever 42 is operated to the lowered position and the bottom chamber 40a of the lift cylinder 40 is communicated with the oil tank, the fork is lowered even when the drive of the hydraulic pump is stopped. As a result, the fork is placed at the raised position and the lift cylinder 40
When the operation of the forklift is stopped (ie, the engine is stopped or the power switch is turned off in the case of a battery car) while the operation of the forklift is stopped, a third person or an operator erroneously operates the lift lever 42 to the lowered position. There was a problem that the fork descended.

When the lift lever 42 is operated to the neutral position and the load applied to the hydraulic oil in the bottom chamber 40a of the lift cylinder 40 directly acts on the lift control valve 41, the spool valve is used. A large hydraulic pressure is applied to the lift control valve 41, and hydraulic oil gradually leaks from the sliding surface. As a result, there is a problem that the lift control valve 41 is disposed at the neutral position in a state where the fork is disposed at the ascending position, and if the fork is left in that state, the fork naturally descends.

Therefore, there has been proposed a forklift in which the fork does not descend when the hydraulic pump is stopped, that is, has a lift lock function. As a typical example of a hydraulic circuit as the lock hydraulic circuit, for example, FIG.
1 and FIG. 12 are known. As shown in FIGS. 11 and 12, the lift control valve 41
Pilot operated check valves 46 and 47 for regulating the flow of hydraulic oil from the bottom chamber 40a to the lift control valve 41 are provided in series in the middle of a pipe line 43 connected to the bottom chamber 40a of the lift cylinder 40. A pilot pressure supply means capable of supplying a pilot pressure for opening the pilot operation check valves 46 and 47 only when the hydraulic pump P is driven is provided.

In an emergency, the fork can be lowered while the hydraulic pump P is not driven, ie, in order to release the lift lock function, one end communicates with the bottom chamber 40a of the lift cylinder 40 and the other end returns. Road 45
A needle valve 48 is provided as an unlocking on-off valve that communicates with the oil tank T via the. In the case of the hydraulic circuit shown in FIG. 11, when the needle valve 48 is opened, the hydraulic oil in the bottom chamber 40a returns to the oil tank T via the needle valve 48, so that the fork can gradually descend. In the case of the hydraulic circuit shown in FIG. 12, when the needle valve 48 is opened, the operating oil in the bottom chamber 40 a
8, the pilot operation check valve 47 is opened and the bottom chamber 40a is opened.
The hydraulic oil is supplied to the oil tank T via the pilot operated check valve and the lift control valve 41 disposed at the lowered position.
The fork can descend quickly by returning to.

[0008]

By the way, as shown in FIG. 13, a conventional needle valve 48 has a flow path 49 and a flow path 5.
The position of a valve stem 48a for shutting off the valve stem 0 is adjusted (flow rate adjustment) by a screw 48b formed integrally with the valve stem 48a. When opening the needle valve 48,
b, and since the needle valve 48 is disposed in the instrument panel of the forklift, the instrument panel must first be removed before the needle valve 48 is opened. This is not desirable when the lift lock function is quickly released and the fork is lowered in an emergency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an industrial vehicle capable of easily releasing the attachment of the industrial vehicle from the locked state, facilitating the production management of the industrial vehicle, and reducing the production cost of the industrial vehicle. It is to provide a hydraulic control device.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a cylinder in which a piston rod is extended to move an attachment upward, and a piston rod is contracted to move the attachment downward. A hydraulic pump that discharges hydraulic oil, a position at which the hydraulic oil is supplied to the cylinder to extend the piston rod, and a position at which the supplied hydraulic oil is discharged from the cylinder to the tank to contract the piston rod. A control valve that switches to three positions based on the operation of a cylinder drive operation lever to stop the supply and discharge of the hydraulic oil to and from the cylinder to stop the piston rod and stop the attachment, and the control valve; When the drive of the hydraulic pump is stopped with respect to a pipe provided between Lock hydraulic circuit for blocking discharge of hydraulic oil from the control valve to the control valve, and unlocking on-off valve for forcibly discharging hydraulic oil supplied to the cylinder to the tank regardless of the three positions of the control valve In the hydraulic control device for an industrial vehicle having:
A second operating lever that opens and closes the lock on-off valve, and an operating force that transmits to the lock on-off valve an operating force for opening and closing the unlocking on-off valve based on the operation of the second operating lever. The gist of the present invention is to include a transmission mechanism.

According to a second aspect of the present invention, in the hydraulic control device for an industrial vehicle according to the first aspect, the second operating lever is a cylinder driving operating lever for switching the control valve. The gist of the invention is to operate the cylinder drive operation lever to an operation position for contracting the piston rod to open and close the lock release on-off valve via the operating force transmission mechanism.

According to a third aspect of the present invention, in the hydraulic control device for an industrial vehicle according to the first aspect, the second operating lever is a cylinder driving operating lever for switching the control valve. The gist of the invention is to operate the cylinder drive operation lever to an operation position other than the three positions to open and close the lock release on-off valve via the operating force transmission mechanism.

According to a fourth aspect of the present invention, in the hydraulic control apparatus for an industrial vehicle according to any one of the first to third aspects,
The operating force transmitting mechanism is a link mechanism, and the second
The gist of the present invention is to convert the operation of the turning operation of the operation lever into the opening and closing operation of the lock release on-off valve.

According to a fifth aspect of the present invention, in the hydraulic control device for an industrial vehicle according to any one of the first to fourth aspects,
At least one of the connection between the second operation lever and the operation force transmission mechanism, the connection between the operation force transmission mechanism and the unlocking on-off valve, and the connection inside the operation force transmission mechanism for enabling the operation force transmission mechanism. The point is that one connection is performed by a detachable connection means.

According to a sixth aspect of the present invention, in the hydraulic control device for an industrial vehicle according to any one of the first to fifth aspects,
The gist of the lock release on-off valve is that an elastic force is constantly urged in a closing direction by an elastic member.

According to the first aspect of the present invention, when the second operating lever is operated, the operating force is transmitted to the operating force transmitting mechanism to open and close the unlocking on-off valve. it can. Therefore, as compared with the conventional screw rotation, the industrial oil can be easily discharged by forcibly discharging the hydraulic oil supplied to the cylinder to the tank irrespective of the three positions of the control valve only by operating the second operation lever. Can be released from the locked state.

According to the second and third aspects of the present invention, when the cylinder drive operating lever for switching the control valve is operated, the operating force is transmitted to the operating force transmitting mechanism to open and close the unlocking on-off valve. can do. Therefore, the attachment of the industrial vehicle can be easily released from the locked state by forcibly discharging the hydraulic oil supplied to the cylinder to the tank simply by operating the operation lever for driving the cylinder, as compared with turning a conventional screw. be able to.

Further, it is not necessary to provide a dedicated second operation lever for opening and closing the lock on-off valve, and the number of components of the hydraulic control device for an industrial vehicle can be reduced. According to the fourth aspect of the present invention, the operation of rotating the second operation lever can be easily converted to the operation of opening and closing the unlocking on-off valve.

According to the fifth aspect of the present invention, if any one of the connections made by the detachable connecting means is disconnected, the unlocking on-off valve is opened via the operating force transmission mechanism. It cannot be opened and closed, and the user can easily switch between prohibition of release of the lift lock function and release of the lift lock function.

According to the sixth aspect of the invention, when the locked state is not released by the elastic force of the elastic member, the unlocking on-off valve is securely maintained in the closed state.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is embodied in a hydraulic control device for a forklift as an industrial vehicle will be described below with reference to FIGS. In this embodiment, it is assumed that a lift lock function is provided and the hydraulic circuit of FIG. 11 or FIG. 12 is used.

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

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

In the front of the cab 10, a steering wheel 11,
A lift lever 12 as a cylinder driving operation lever and a tilt lever 13 as a tilt operation means are provided. In FIG. 1, both levers 12,
13 are shown in an overlapping state. Lift lever 12
The lift cylinder 4 is extended and contracted by the operation of, and the tilt cylinder 9 is extended and contracted by the operation of the tilt lever 13.

An operation lever 14 as a second operation lever is provided at a predetermined position on the front frame 2a at the front of the cab 10. Further, as shown in FIG. 2, the operation lever 14 is disposed in the protective cover 15 so as not to be operated except in an emergency.

As shown in FIG. 2, the operation lever 14 is rotatably supported by an L-shaped support arm 16 fixed to the front frame 2a. A lever side wire fixing member 14 a is fixed to the operation lever 14. The other end of the wire 17 whose one end is connected to the lever side wire fixing member 14a is connected to a link mechanism 19 as an operating force transmission mechanism for opening a needle valve 18 as an unlocking on-off valve. . A guide 20 for guiding and supporting the wire 17 is provided between the lever-side wire fixing member 14a and the link mechanism 19.

The link mechanism 19 includes a support member 22 fixed to the valve element 18a of the needle valve 18, and a support member 22
And a lever 23 rotatably connected to the lever 23. The proximal end 23a of the lever 23 is rotatably connected to the support member 22 by a bolt 24 as a detachable connecting means.
A bolt 25 as a connecting means to which the link mechanism side wire fixing member 21 to which the connecting member 7 is connected is detachable is fixed. A bolt 26 as a connecting means capable of attaching and detaching the needle valve 18 as an unlocking on-off valve at a predetermined intermediate position of the lever 23
Are connected rotatably.

As shown in FIG. 2, the needle valve 18 has a valve element 18a, a valve rod 18d for opening and closing the flow paths 18b and 18c, and a spring as an elastic member for urging and holding the valve rod 18d. 18e. The valve stem 18d is composed of a flow path blocking part 18f and a valve opening part 18g formed so as to extend upward from the flow path blocking part 18f and to be exposed outside the valve element 18a. The flow path blocking unit 18f
The spring 18e is pressed and held from above by a spring 18e so as to be vertically movable along a guide portion 18h provided on the valve element 18a and to always shut off the flow path 18b and the flow path 18c.
The spring 18e is a coil spring 18e, one end of which is in contact with the flow path blocking portion 18f, and the other end is pressed and held by a holding plate 18i. That is, the spring 18e is sandwiched and held by the flow path blocking portion 18f and the holding plate 18i. The holding plate 18i is provided with a guide hole 18j that penetrates the valve opening 18g at a substantially central position thereof, and is fixed to the valve body 18a with a screw 18k. A connection hole 18m for connecting to the lever 23 is formed at the tip of the valve opening portion 18g. The needle valve 18 is connected to a link mechanism 19 via a valve opening 18g, and is fixed at a predetermined position on the vehicle body frame 2. The flow path 18b on the entrance side communicates with the bottom chamber of the lift cylinder 4 (not shown), and the flow path 18b on the exit side communicates with an oil tank (not shown).

Next, the operation of opening the needle valve 18 will be described. As shown in FIG. 2, when the operation lever 14 is tilted in the direction of the arrow, the wire 17 is pulled, and the tip 23 b of the lever 23 connected to the other end of the wire 17 via the link mechanism side wire fixing member 21 becomes Lifted upwards. At the same time, the valve opening portion 1 of the needle valve 18
8g is also lifted upward. At this time, the flow passage blocking portion 18f of the needle valve 18 is lifted together with the valve opening portion 18g against the elasticity of the spring 18e, so that the flow passage 18b and the flow passage 18c are conducted, that is, the needle valve 18 is opened. You. When the operating lever 14 is released, since the wire 17 is not pulled, the flow path cut-off portion 18f of the needle valve 18 returns to the original position so as to cut off the flow path 18b and the flow path 18c again by the elasticity of the spring 18e. Returned to. At this time, the lever 23 and the operation lever 14 are returned to the original positions by being pulled in the opposite directions by the valve rod 18d.

Next, the features of the hydraulic control device configured as described above will be described. (1) In the present embodiment, the needle valve 18 is
The link mechanism 19 is connected to the operation lever 14 via a wire 17 via a valve opening 18g of the valve. Therefore, as described above, the needle valve 18 can be easily opened by tilting the operation lever 14. As a result, the lift lock function is easily released and the fork 6 is lowered without removing the instrument panel even during operation stoppage of the forklift 1 in a state where the fork 6 is arranged at the raised position and the operation of the lift cylinder 4 is stopped in an emergency. be able to.

(2) In this embodiment, the lever 23 of the link mechanism 19 has its base end 23a connected by a bolt 24 as a detachable connecting means, and its distal end 23b serves as a detachable connecting means. Are connected to the link mechanism side wire fixing member 21 by the bolts 25. In addition, lever 2
The needle valve 18 is connected between the proximal end 23a and the distal end 23b of the third by a bolt 26 as a detachable connecting means. Therefore, the bolt 26 or the bolt 25 is not attached to the user who wants to prohibit the release of the lift lock function.
g or lever 23 and link mechanism side wire fixing member 21
It is easy to respond simply by not connecting. As a result, there is no need to separately manufacture a lift lock prohibition release lift and a lift lock function releasable lift, which makes it easier to manage the production of the lift and reduces the production cost of the lift.

(3) In the present embodiment, the flow path blocking portion 18f of the needle valve 18 is urged by a spring 18e as an elastic member so as to always block the flow path 18b and the flow path 18c. . Accordingly, since the flow path 18b and the flow path 18c are shut off, that is, the bottom chamber of the lift cylinder 4 and the oil tank are shut off, the lift lock for surely preventing the fork 6 from lowering when the hydraulic pump is not driven is stopped. Function is valid.

(4) In this embodiment, the operation lever 14 as the emergency fork lowering operation means is provided with the protective cover 15
Is located within. Therefore, it is possible to prevent a third person or an operator from accidentally tilting the operation lever 14 except in an emergency.

The link mechanism 19 of the present embodiment may be modified as shown in FIG. To elaborate,
As shown in FIG. 3, the lever 23 of the link mechanism 19 has its proximal end 23a connected to the valve opening 18g of the needle valve 18 by a bolt 24 as a detachable connecting means, and its distal end 23b is detachable. It is connected to the link mechanism side wire fixing member 21 by a bolt 25 as connecting means. The support member 22 is located between the base end 23a and the tip 23b of the lever 23.
Are connected by bolts 26 as detachable connecting means, and the lever 23 is rotatably supported by the support member 22. The wire 17 connected to the link mechanism side wire fixing member 21 is connected to the operation lever 14 after passing through the guide 20.

In this case, when the operating lever 14 is tilted in the direction of the arrow, the wire 17 is pulled, and the tip 23b of the lever 23 connected to the other end of the wire 17 via the wire fixing member 21 on the link mechanism is moved downward. Can be lowered towards
Then, the base end 23a of the lever 23 is raised upward by the action of the lever. At the same time, the valve opening 18g of the needle valve 18 connected to the proximal end 23a of the lever 23 is lifted upward. At this time, the flow path blocking portion 18f of the needle valve 18 is lifted together with the valve opening portion 18g against the elasticity of the spring 18e, so that the flow path 18b and the flow path 18c are conducted.
Is released. When the operating lever 14 is released, since the wire 17 is not pulled, the flow path cut-off portion 18f of the needle valve 18 is again moved by the elasticity of the spring 18e.
And the flow path 18c is returned to the original position so as to shut off.
At this time, the lever 23 and the operation lever 14 are moved to the valve stem 18d.
It is returned to its original position by being pulled in the opposite direction. In this case, the same effect as described above can be obtained.

In the present embodiment, the operation lever 14 is disposed at a predetermined position in front of the cab 10. However, the operation lever 14 is disposed at a position where the operation of the operation lever 14 is not hindered, for example, at a predetermined position of the body frame 2. May be implemented. In this case, the same effect as described above can be obtained.

In this embodiment, it is stated that when the operating lever 14 is depressed, the needle valve 18 is opened. However, "depressing the operating lever 14" means that the operating lever 14 is operated so that the wire 17 is pulled. It means to do.

(Second Embodiment) Hereinafter, a second embodiment in which the present invention is embodied in a hydraulic control device for a forklift as an industrial vehicle will be described with reference to FIGS. This embodiment is different from the first embodiment in that the link mechanism is directly connected to the lift lever. For convenience of explanation,
The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Only different points will be described in detail. In this embodiment, it is assumed that a lift lock function is provided and the hydraulic circuit of FIG. 11 or FIG. 12 is used.

As shown in FIG. 4, a lift control valve 27 disposed in a lift hydraulic control circuit (not shown) as a control valve for controlling the lifting and lowering of the fork 6 is a direct-acting spool valve. The control end is connected to the base end of the connecting rod 28. The lift control valve 27 can be switched to three states a, b, and c by the vertical movement of the connecting rod 28. In response to the three states, the fork 6 is operated so as to rise, neutral, and descend. The tip of the connecting rod 28 is rotatably connected to the rotating part 12 a of the lift lever 12. The lift lever 12 is attached to the front portion of the cab 10 shown in FIG. 1 so that the rotating portion 12a is rotatably supported by the support pin 12b. Connecting rod 2
A link mechanism 19 is connected to an intermediate predetermined position of the link 8.

The lever 23 of the link mechanism 19 has its tip 2
3b is rotatably connected to the connecting rod 28 by a bolt 25 as detachable connecting means, and the base end 23a of the needle valve 1 is connected to a pin 29 fixed to the base end 23a.
8 is connected to the valve opening 18g. A support member 22 is rotatably connected between a base end 23a and a front end 23b of the lever 23 by a bolt 26 as a detachable connection means. Note that a pin hole 18n for connecting to the lever 23 formed at the tip of the valve opening portion 18g is provided in FIG.
As shown in (a) to (d), the pin 29 is formed to be a long hole that allows the pin 29 to move up and down.

Next, the operation of opening the needle valve 18 will be described. As shown in FIG. 4, when the lift lever 12 is switched from the raised position A to the neutral position B in the direction of the arrow, the connecting rod 28 rotates the rotating portion 12 a of the lift lever 12 counterclockwise. The lift control valve 27 is switched from the state a to the state b. At the same time, the tip 23b of the lever 23 connected to the connecting rod 28 is lowered downward. Then, the base end 23a of the lever 23 is raised upward by the levering action. The pin 29 fixed to the proximal end 23a of the lever 23 is shown in FIG. 5B from the lower end of the pin hole 18n shown in FIG. It moves upward so as to be located slightly above the pin hole 18n. At this time, the valve stem 18d is not lifted, and the flow path 18b and the flow path 18c are connected to the flow path shutoff portion 1 of the needle valve 18 urged by the spring 18e.
The fork 6 is maintained in a neutral state while being shut off from 8f.

Further, as shown in FIG.
2 is switched from the neutral position B to the lowered position C along the direction of the arrow, the connecting rod 28
Is further lowered by the counterclockwise rotation of the rotating portion 12a, and the lift control valve 27 is switched from the b state position to the c state position. At the same time, the tip 23b of the lever 23 connected to the connecting rod 28 is further lowered downward. Then, the base end 23a of the lever 23 is raised upward by the action of the lever. The pin 29 fixed to the base end 23 a of the lever 23 is provided with the pin hole 18.
The valve rod 18d is lifted by moving upward from a position slightly above the center of n to a position shown in FIG. 5D through a position shown in FIG. 5C which contacts the upper end of the pin hole 18n. At this time, the passage blocking portion 18f of the needle valve 18 is
The flow path 18b and the flow path 18c are electrically connected to each other, that is, the needle valve 18 is opened by being lifted together with the valve stem 18d against the elasticity of the valve rod 18d. Therefore, lift cylinder 4
When the hydraulic oil in the bottom chamber returns to the oil tank via a needle valve, a pilot-operated check valve (not shown), and a lift control valve 27 disposed at a lowered position, the fork 6 is lowered.

Conversely, when the lift lever 12 is switched from the C position to the B position or the A position in the direction of the arrow, the connecting rod 28 is moved upward by the clockwise rotation of the rotating portion 12a of the lift lever 12, and The lift control valve 27 is switched from the neutral state c to the state b or the state a. At the same time, the tip 23b of the lever 23 connected to the connecting rod 28 is raised upward. Then, the base end 23a of the lever 23 is lowered downward by the action of the lever. When the pin 29 fixed to the base end 23a of the lever 23 is lowered downward from a state in which the pin 29 is in contact with the upper end of the pin hole 18n, the flow path blocking portion 18f of the needle valve 18 is re-formed by the elastic force of the spring 18e. 18b and the flow path 18c are returned to their original positions so as to be shut off. At this time, the fork 6 cannot descend.

Accordingly, the hydraulic control device configured as described above has the following features in addition to the feature (3) of the hydraulic control device of the first embodiment. (1) In the present embodiment, the tip 23b of the lever 23 of the link mechanism 19 is connected to the connecting rod 28 of the lift lever 12, and is moved up and down according to the operation of the lift lever 12. Further, a pin hole 18n provided in the valve opening portion 18g of the needle valve 18 is formed to be a long hole that allows the pin 29 to move up and down. Accordingly, when the lift lever 12 is operated to the lower position C, the needle valve 18 is opened. When the lift lever 12 is operated to a position other than the lower position C, for example, the position A or B, the needle valve 18 is opened. Will not be released. As a result, the fork 6 can be easily lowered by operating the lift lever 12 to the lowering position even when the operation of the forklift 1 is stopped in a state where the fork 6 is arranged at the raised position and the operation of the lift cylinder 4 is stopped in an emergency. be able to.

(2) In the present embodiment, the lever 23 of the link mechanism 19 is directly connected to the lift lever 12 and is moved up and down according to the operation of the lift lever 12. Accordingly, components such as an operation lever, a wire, a guide, and a wire fixing member necessary for operating the lever 23 of the link mechanism 19 in the first embodiment can be omitted. As a result, the number of parts of the lift and the manufacturing cost can be reduced.

(3) In this embodiment, the lever 23 of the link mechanism 19 has its tip 23b connected to the connecting rod 28 by a bolt 25 as a detachable connecting means.
The base end 23a is connected to a valve opening 18g of the needle valve 18 via a pin 29 fixed to the base end 23a. Further, the support member 22 is connected to the lever 23 by a bolt 26 as a detachable connecting means, and the lever 23 is rotatably supported by the support member 22. Therefore, the user who wants to prohibit the release of the lift lock function can easily respond to the user by not attaching the bolt 26 or the bolt 25, that is, not connecting the lever 23 to the support member 22 or the lever 23 to the connecting rod 28. be able to. As a result, there is no need to separately manufacture a lift lock prohibition release lift and a lift lock function releasable lift, which makes it easier to manage the production of the lift and reduces the production cost of the lift.

In this embodiment, the lift control valve 2
7 is actually from position b to position a (lift lever 12
(A position), and the flow rate can be controlled continuously from the b position to the c position (C position of the lift lever 12). Here, as shown in FIG.
The point at which the valve opening portion 18g of FIG. 8 comes into contact with the upper end of the pin hole 18n and starts moving is defined by a lift lever operating position B shown in FIG.
D (arbitrary position) between C and C. in this case,
The lift lever operating force is, as shown in FIG.
While -D is only the force α against the spring force of the lift control valve 27, between DC and DC, the force against the needle valve flow path interrupting spring 18e is added to the above-mentioned force, so that the operation becomes β. It can alert people.

(Third Embodiment) A third embodiment in which the present invention is embodied in a hydraulic control device for a forklift as an industrial vehicle will be described with reference to FIGS. In the present embodiment, the connection position of the lift lever connected to the link mechanism and the operation position of the lift lever are different from those of the second embodiment. For convenience of explanation, the same parts as those in the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Only different points will be described in detail. In this embodiment, it is assumed that a lift lock function is provided and the hydraulic circuit of FIG. 11 or FIG. 12 is used.

As shown in FIG. 7, the connecting rod 28 of the lift lever 12 is composed of a lift control valve connecting portion 28a and a lift lever connecting portion 28b.
The lift lever connection portion 28b is connected to the lift lever connection portion 28b by a rotation connection member 30. That is, one end of the lift lever connecting portion 28b is rotatably connected to the turning portion 12b about the connecting pin 12c as a turning center. Further, the other end of the lift lever connecting portion 28b is fixed to the rotation connecting member 30.
The distal end of the lift control valve connecting portion 28a is rotatably connected to the rotary connecting member 30 about a connecting pin 30a as a rotation center. Then, raise the lift lever 12 to A
When operating between the position C and the position C, the spool of the lift control valve 27 moves up and down in FIG. 7 via the lift lever connecting portion 28b, the rotary connecting member 30, and the lift control valve connecting portion 28a. The control valve 27 is switched to three state positions a, b, and c. When the lift lever 12 is operated from the C position to the D position, the spool of the lift control valve 27 holds the position c in FIG. 7 and further downward movement is regulated, and the spool is rotated based on the downward movement regulation. The connecting member 30 is in the K direction (clockwise in FIG. 7).
It is designed to rotate.

An operating pin 31 is fixed to a predetermined position of the rotation connecting member 30. Lever 2 of link mechanism 19
An elongate hole 23c is formed at the tip 23b of 3. The operating pin 31 is inserted through the elongated hole 23c, and the lever 23 and the rotation connection member 30 are connected. A pin 29 is fixed to the base end 23a of the lever 23,
By inserting the pin 29 into a pin hole 18n formed in the valve opening 18g of the needle valve 18, the lever 23
And the needle valve 18 are connected. The support member 22 is rotatably connected between a base end 23a and a front end 23b of the lever 23 by a bolt 26 as a detachable connection means.

Next, the operation of opening the needle valve 18 will be described. As shown in FIG. 7, when the lift lever 12 is switched from the raised position A to the neutral position B in the direction of the arrow, the connecting rod 28 rotates counterclockwise of the rotating portion 12a of the lift lever 12. The lift control valve 27 is switched from the state a to the state b. At the same time, the tip 23b of the lever 23 connected to the connecting rod 28 is lowered downward. Then, the base end 23a of the lever 23 is raised upward by the action of the lever. The pin 29 fixed to the base end 23a of the lever 23 is moved from the lower end of the pin hole 18n shown in FIG.
It moves upward to a substantially middle position of the pin hole 18n shown in FIG.
At this time, the valve stem 18d is not lifted, and the fork 6 is in the neutral state while the flow path 18b and the flow path 18c are shut off by the flow path shutoff portion 18f of the needle valve 18 urged by the spring 18e. Is held.

When the lift lever 12 is switched from the neutral position B to the lowered position C in the direction of the arrow, the connecting rod 28 is lowered by the counterclockwise rotation of the rotating portion 12a of the lift lever 12. Actuated and lift control valve 27
Is switched from the b state position to the c state position. At the same time, the tip 2 of the lever 23 connected to the connecting rod 28
3b is further lowered downward. Then, the base end 23a of the lever 23 is further raised upward by the action of the lever. The pin 29 fixed to the base end 23a of the lever 23 extends along the pin hole 18n at the distal end of the valve opening 18g from a substantially intermediate position of the pin hole 18n shown in FIG. 8B to the pin shown in FIG. It moves upward so as to contact the upper end of the hole 18n. At this time, the valve stem 18d is not lifted, and the flow path 18b and the flow path 18c are blocked by the flow path blocking portion 18f of the needle valve 18 urged by the spring 18e. When the drive is stopped, the fork 6 cannot be lowered. Since the lift control valve 27 has been switched to the lowered position (position c), the fork 6 can be lowered in the driving state of the hydraulic pump.

Further, as shown in FIG. 7, when the lift lever 12 is switched from the lower position C to the emergency lower position D in the direction of the arrow, the lift lever connecting portion 28b of the connecting rod 28 Is further lowered by the counterclockwise rotation of the rotating portion 12a of the connecting rod 2a.
Since the lift control valve connecting portion 28a of FIG. 8 cannot move down further, the rotary connecting member 30 is rotated in the direction K shown in FIG. At this time, since the operation pin 31 fixed to the rotation connecting member 30 is moved down, the rotation connecting member 3
The tip 23b of the lever 23 connected to 0 is further lowered downward. And the base end 23 of the lever 23
a is further raised upward by the action of the lever. Pin 29 fixed to base end 23a of lever 23
8 is in contact with the upper end of the pin hole 18n in FIG.
The valve rod 18d is lifted by moving upward from the position shown in FIG. 8C to the position shown in FIG. At this time, the flow path blocking portion 18f of the needle valve 18 is lifted together with the valve rod 18d against the elasticity of the spring 18e, so that the flow path 18b and the flow path 18c are conducted, that is, the needle valve 18 is opened. . Accordingly, the hydraulic oil in the bottom oil chamber of the lift cylinder 4 is supplied with a needle valve or a pilot-operated check valve (not shown), and the lift control valve 2 disposed at the lowered position.
By returning to the oil tank via 7, the fork 6 is lowered.

Conversely, when the lift lever 12 is switched from the D position to the C position in the direction of the arrow, the lift lever connecting portion 28b of the connecting rod 28 is moved to the rotating portion 12 of the lift lever 12.
By being moved up by the clockwise rotation of a,
The rotation connecting member 30 returns to the original position. At this time, lever 2
The tip 23b of the third member 3 is raised upward by the action of the operating pin 31 which is moved up together with the rotary connecting member 30. Then, the base end 23a of the lever 23 is lowered downward by the action of the lever. With the downward movement of the pin 29 fixed to the base end 23a of the lever 23, the needle valve 1
8 is returned to the original position so that the flow path 18b and the flow path 18c are again blocked by the elastic force of the spring 18e.

Therefore, the hydraulic control device configured as described above has the following features in addition to the features (3) of the hydraulic control device of the first embodiment and the features (2) of the hydraulic control device of the second embodiment. There is. (1) In the present embodiment, the connecting rod 28 of the lift lever 12
Is the lift control valve connecting portion 28a and the lift lever connecting portion 2
8b, the lift control valve connecting portion 28a and the lift lever connecting portion 28b are connected by a rotary connecting member 30. Further, the link mechanism 19 is provided with a tip 23 of the lever 23.
The operation pin 31 fixed to the rotation connection member 30 is inserted through the long hole 23c formed in the connection rod 30 to be connected to the connection rod 28. Therefore, when the lift lever 12 is operated in the normal operation range, that is, the range from the position A to the position C, the needle valve 18 is not opened, and the fork 6 cannot be lowered in a state in which the hydraulic pump is stopped. A third party or a worker may voluntarily raise the lift lever 12
Is operated from the C position to the D position of the emergency lowering position, the needle valve 18 is opened with the rotation of the rotary connecting member 30, and the fork 6 can be lowered. As a result, it is possible to prevent the fork 6 from being lowered by an erroneous operation of the lift lever 12 to the lowered position by a third party or an operator while the drive of the hydraulic pump is stopped. In addition, even when the forklift 1 is stopped in the state where the operation of the lift cylinder 4 is stopped by disposing the fork 6 at the raised position, the fork 6 can be easily lowered by operating the lift lever 12 to the emergency lowering position D position. Can be done. Further, in this case, as shown in FIG. 9, the operation force of the lift lever 12 increases from α to β, so that an erroneous operation can be recognized.

(2) In this embodiment, the support member 2
2 is leveraged by bolts 26 as detachable connecting means.
The lever 23 is rotatably supported by the support member 22. Therefore, a user who wants to prohibit the release of the lift lock function can easily respond by not attaching the bolt 26, that is, not connecting the lever 23 and the support member 22. As a result, there is no need to separately manufacture a lift lock prohibition release lift and a lift lock function releasable lift, which makes it easier to manage the production of the lift and reduces the production cost of the lift.

The above embodiments and other examples may be modified as follows. ○ Attachments other than forks as cargo handling attachments, such as roll clamps used for transporting roll paper, block clamps used for transporting blocks or stacking work, or coiled or cylindrical wires and cables wound in coils. The invention may be applied to an industrial vehicle equipped with a ram or the like used for carrying loads.

[0058]

As described in detail above, according to the first to fifth aspects of the present invention, the attachment of the industrial vehicle can be easily released from the locked state.

Further, according to the invention of claim 5,
It is not necessary to separately manufacture an industrial vehicle and an unlockable industrial vehicle in which the lock of the attachment is not required to be released separately, which facilitates the production management of the industrial vehicle and reduces the manufacturing cost of the industrial vehicle. it can.

According to the sixth aspect of the present invention, the unlocking on-off valve can be reliably held in the closed state when the locked state is not released.

[Brief description of the drawings]

FIG. 1 is a side view of a forklift.

FIG. 2 is a sectional view of an essential part of the hydraulic control device according to the first embodiment;

FIG. 3 is a sectional view of a main part of a hydraulic control device according to another example.

FIG. 4 is a sectional view of a main part of a hydraulic control device according to a second embodiment.

FIG. 5 is an enlarged explanatory view of a main part of a valve opening portion of an unlocking on-off valve of the hydraulic control device.

FIG. 6 is an explanatory diagram showing a relationship between a lift lever operation position and a lift lever operation force.

FIG. 7 is a sectional view of a main part of a hydraulic control device according to a third embodiment.

FIG. 8 is an enlarged explanatory view of a main part of a valve opening portion of an unlocking on-off valve of the hydraulic control device.

FIG. 9 is an explanatory diagram showing a relationship between a lift lever operation position and a lift lever operation force.

FIG. 10 is a main part of a hydraulic circuit of a conventional forklift.

FIG. 11 is an essential part of a hydraulic circuit of a forklift having a lift lock function.

FIG. 12 is an essential part of a hydraulic circuit of a forklift having a lift lock function.

FIG. 13 is a sectional view of a main part of a conventional needle valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 4 ... Lift cylinder, 6 ... Fork as an attachment, 12 ... Lift lever as an operation lever for driving a cylinder, 14 ...
Operation lever as second operation lever, 17 ... wire, 1
8. Needle valve as unlocking on-off valve, 18d ...
Valve stem, 18e: spring as elastic member, 18g: valve opening, 19: link mechanism as operating force transmission mechanism, 22 ...
Support members, 23: levers, 24-26: bolts as detachable connection means, 27: lift control valves as control valves, 30: rotating connection members.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16K 31/44 F16K 31/44 C G05G 9/02 G05G 9/02

Claims (6)

[Claims] 1. A cylinder for extending an attachment by extending a piston rod, and for lowering an attachment by contracting a piston rod, a hydraulic pump for discharging hydraulic oil, and supplying the hydraulic oil to the cylinder. A position where the piston rod is extended, a position where the supplied hydraulic oil is discharged from the cylinder to the tank and the piston rod is contracted, and a position where the supply and discharge of the hydraulic oil to and from the cylinder is stopped to stop the piston rod. A control valve that is switched to three positions for stopping the attachment by operation of a cylinder driving operation lever, and a pipe provided between the control valve and the cylinder to supply and discharge the hydraulic oil. A lock hydraulic circuit that shuts off discharge of hydraulic oil from the cylinder to the control valve when the drive of the hydraulic pump is stopped; 3 the hydraulic oil supplied to the cylinder of the control valve
A hydraulic control device for an industrial vehicle having a lock release on-off valve forcibly discharging the tank to the tank irrespective of the position, a second operation lever provided in a driver's cab, for opening and closing the lock on-off valve. An hydraulic control device for an industrial vehicle, comprising: an operating force transmitting mechanism that transmits an operating force for opening and closing the unlocking on-off valve based on an operation of the second operating lever to the locking on-off valve. 2. The hydraulic control device for an industrial vehicle according to claim 1, wherein the second operation lever is a cylinder drive operation lever that switches the control valve. A hydraulic control device for an industrial vehicle, wherein the lock release on-off valve is opened and closed via the operating force transmission mechanism by operating to an operation position where the piston rod is contracted. 3. The hydraulic control device for an industrial vehicle according to claim 1, wherein the second operation lever is a cylinder drive operation lever that switches the control valve. A hydraulic control device for an industrial vehicle, wherein the lock release on-off valve is opened and closed via the operating force transmission mechanism by operating to an operation position other than the three positions. 4. The hydraulic control device for an industrial vehicle according to claim 1, wherein the operating force transmitting mechanism is a link mechanism, and
A hydraulic control device for an industrial vehicle, wherein the operation of turning the operation lever is converted into the operation of opening and closing an unlocking on-off valve. 5. The hydraulic control device for an industrial vehicle according to claim 1, wherein the second operation lever is connected to an operating force transmitting mechanism, the operating force transmitting mechanism is a lock release opening / closing valve. A hydraulic control device for an industrial vehicle, wherein at least one of the connections within the operating force transmission mechanism for making the operating force transmission mechanism effective and the connection with the second connection is performed by detachable connection means. 6. The hydraulic control device for an industrial vehicle according to claim 1, wherein the unlocking on-off valve is always biased in a closing direction by an elastic member. Vehicle hydraulic control device.