JP2004216970A - Controlling device for forklift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controlling device for a forklift capable of preventing raising wheels at the time of traveling under a lock condition by a suspension lock device. <P>SOLUTION: Wheels are installed to a vehicle body via a suspension mechanism movable upward and downward, and a suspension lock device for locking/unlocking the upward and downward movement of the wheels is provided between the suspension mechanism and the vehicle body. The device comprises a detection means for detecting wheel pressure applied to the wheel, and a control means for making the suspension lock device into an unlock condition when the wheel pressure of the wheel detected by the detection means is decreased under a lock condition of the suspension lock device. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a forklift, and more particularly to a technology that enables a vehicle to stably travel on an uneven road surface or an inclined road surface.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a forklift, for example, as shown in the following document, a lock cylinder is provided between a vehicle body and a suspension mechanism that supports wheels, and by temporarily preventing the telescopic operation of the lock cylinder, temporarily or instantaneously. The function of the suspension mechanism is limited, and by providing such a so-called suspension lock device, stability during cargo handling or turning is ensured.
[0003]
[Reference 1]
Japanese Patent No. 3079823 [Reference 2]
JP 10-297900 A [Reference 3]
Japanese Patent Application Laid-Open No. 2000-52737
[Problems to be solved by the invention]
However, if the suspension lock device restricts the function of the suspension mechanism, and the vehicle runs on a sloping surface or a concave portion of an uneven road surface, there is a possibility that the wheels that should touch the ground will float if the suspension mechanism is functioning. It is conceivable that if this wheel is a driving wheel or a steering wheel, there is a problem that the forklift cannot be operated temporarily or instantaneously.
[0005]
The present invention has been proposed based on such conventional circumstances, and provides a control device for a forklift capable of preventing a drive wheel, a steering wheel, or the like from floating in a locked state by a suspension lock device. With the goal.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a suspension for vertically moving wheels provided on a vehicle body via a suspension mechanism, and locking / unlocking the vertical movement of the wheels between the suspension mechanism and the vehicle body. A control device for a forklift equipped with a lock device, wherein a detection unit for detecting wheel pressure applied to the wheel, and when the wheel pressure of the wheel detected by the detection unit decreases in a locked state of the suspension lock device. And a control means for unlocking the suspension lock device. A control device for a forklift is constituted by adopting a means characterized by comprising:
[0007]
According to such a configuration, when the wheel pressure of the wheels decreases when the vehicle travels on an uneven road surface or an inclined road surface in the locked state, the suspension lock device is unlocked, so that the suspension mechanism has its original function. As a result, the wheels sufficiently come into contact with the road surface. Therefore, there is no problem that the forklift is inoperable due to temporary lifting of the wheels or insufficient wheel pressure, and the vehicle can always travel in a stable state. The detection of the wheel pressure may be performed at least when the vehicle is in the locked state, and may be performed at all times.
[0008]
In the present invention, the detecting means for detecting the wheel pressure applied to the wheel may be a means for detecting a load applied to a component of the suspension mechanism such as an axle supporting the wheel or an operation amount of each member. The load applied to the members constituting the lock device and the operation amount of each member can be detected.
[0009]
For example, a suspension lock device is provided on the oil passage, a lock cylinder in which the bottom side is fixed to the vehicle body and the head side is fixed to the suspension mechanism, and the bottom side oil chamber and the head side oil chamber communicate with each other through an oil path. In the case of a lock valve that opens and closes the oil passage, the detection means may be a bottom oil chamber or a pressure detector that measures a pressure in an oil passage between the bottom oil chamber and the lock cylinder. At this time, the control means is configured to, when the detection output of the pressure detector becomes equal to or less than a predetermined value, operate the lock valve so as to open the oil passage and put the suspension lock device in the unlocked state. Just fine.
[0010]
According to this, it is possible to relatively easily detect a decrease in the wheel pressure of the wheel from the measured decrease in the oil pressure in the oil passage between the bottom oil chamber and the bottom oil chamber and the lock cylinder. When the pressure drops below a predetermined value, the suspension lock device is unlocked, so that the wheels can be brought into contact with the road surface.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention.
[0012]
As shown in FIG. 1, straddle arms 3 are respectively fixed to the front and rear ends of the front of a vehicle body 2 of a reach type forklift 1 so as to protrude forward. A guiding mast 5 is established to be movable back and forth. Left and right front wheels 6, 6 are rotatably attached to the straddle arms 3, respectively. A drive wheel 7 also serving as a steering wheel is attached to a lower rear portion of the vehicle body 2, and supports the vehicle body 2 so that the vehicle body 2 travels. A driven caster wheel 8 is attached. Further, the vehicle body 2 is provided with various operation levers 9 for operating the mast 5 and the fork 4, and an accelerator 10 for rotating the drive wheels 7 is provided, and a steering handle for steering is provided. 11 are provided. Although not shown, a drive wheel braking device including a brake pedal operated by a driver and a disc brake operated by the brake pedal is disposed on the vehicle body 2, and while the brake pedal is being depressed, the drive is stopped. When the wheel brake device is deactivated and the vehicle can run, and when the brake pedal is released, the drive wheel brake device operates to apply a braking force to the drive wheel 7.
[0013]
As shown in FIG. 2, the drive wheels 7 and the caster wheels 8 are supported by the vehicle body 2 via a control linkage 15 as a suspension mechanism. The control linkage 15 includes an upper link 16, a lower link 17, a caster link 18, a main spring 20, and a caster spring 21. The upper link 16 is supported by the vehicle body 2 at the right end and the drive device 25 at the left end by a link pin 26, and the lower link 17 is supported by the vehicle body 2 at the middle and the link pin 26 at the left end by the drive device 25. It is pivoted. The caster link 18 has its left end pivotally supported by the lower link 17 via a link pin 26, and the caster wheel 8 is rotatably attached to the lower right end of the caster link 18, between the upper surface of the caster link 18 and the lower link 17. , A caster spring 21 is disposed. The main spring 20 is provided so as to be sandwiched between the vehicle body 2 and the upper surface of the lower link 17, so that the drive wheel 7 and the caster wheel 8 can move up and down.
[0014]
As shown in FIG. 2, the lock cylinder 22 is fixed to the vehicle body 2 with the piston rod 45 facing downward by a support bracket 49 projecting from the vehicle body 2, and the piston rod 45 is supported by the lower link 17 by the link pin 26. I have. Therefore, for example, when the drive wheel 7 moves up and down during traveling, the piston rod 45 also moves up and down accordingly. Further, a pressure detector 37 is mounted between an upper chamber 41 which is a bottom side oil chamber of the lock cylinder 22 and an oil passage 38 which communicates one end of the lock valve 36. The other end of the lock valve 36 is connected to a lower chamber 42 which is a head-side oil chamber of the lock cylinder 22 via an oil passage 39. The lock cylinder 22 and the lock valve 36 constitute a suspension lock device.
[0015]
As shown in FIG. 3, the control device according to the present embodiment includes a drive wheel encoder 31 for detecting a traveling speed Vd of the drive wheel 7, a potentiometer 32 for detecting a steering angle θ of the drive wheel 7, and a brake pedal. A brake switch 33 that is turned on when depressed to output a brake command signal Br is provided. Then, based on the traveling speed Vd, the steering angle θ, and the brake command signal Br, an inertia force acting on the reach-type forklift 1 traveling by the deriving unit 34 is obtained. 35 closes the lock valve 36 to shut off the inflow and outflow of the hydraulic oil between the upper chamber 41 and the lower chamber 42 of the lock cylinder 22, so that a so-called locked state is established. On the other hand, the output of the pressure detector 37 attached to the oil passage 38 is also input to the control unit 35, and the pressure of the upper chamber 41 of the lock cylinder 22 is constantly measured.
[0016]
In the unlocked state, that is, when the lock valve 36 is open and the hydraulic oil can flow in and out between the upper chamber 41 and the lower chamber 42 in the unlocked state, as described above, the piston rod 45 Since the driving wheel 7 and the caster wheel 8 move up and down because the link 17 is pivotally supported by the link pin 26, the piston 43 and the piston rod 45 also move up and down in the lock cylinder 22 with this. The output of the unit 37 is ignored.
[0017]
When the lock valve 36 is turned on via the control unit 35 to be in a locked state, if the wheel pressure applied to the drive wheel 7 increases as compared with the time when the lock valve 36 is closed, the piston 43 and the piston rod 45 are further pushed in. Therefore, the pressure of the upper chamber 41 increases. Conversely, when the wheel pressure applied to the drive wheels 7 decreases, the pressure in the upper chamber 41 also decreases. Therefore, if the pressure in the upper chamber 41 of the lock cylinder 22 is proportional to the detection output of the pressure detector 37 as shown in FIG. An increase or decrease in wheel pressure can be detected.
[0018]
When the control unit 35 determines that the detection output of the pressure detector 37 is lower than the lower limit set in advance, the control unit 35 turns off the lock valve 36 and operates between the upper chamber 41 and the lower chamber 42. Allows oil to flow in and out (unlocked). As a result, the drive wheel 7 can be lowered to the lower limit, so that it is possible to sufficiently contact the ground even on an inclined road surface or an uneven road surface. When the road surface changes abruptly, as shown in FIG. 2 (exaggeratedly shown in FIG. 2), the drive wheel 7 comes into contact with the ground immediately after floating up from the inclined road surface 50 for a moment. On the other hand, if the change in the road surface is not so rapid, the unlocked state is established when the detection output of the pressure detector 37 is determined to be lower than the lower limit before floating, so that the grounded state of the drive wheels 7 is maintained. . Accordingly, it is possible to prevent the drive wheels 7 from slipping or becoming incapable of steering in the locked state, and stable driving is possible.
[0019]
【The invention's effect】
According to the present invention, even when traveling on an inclined road surface or an uneven road surface in the locked state, when the wheel pressure of the wheel decreases, the wheel is brought into the unlocked state and the wheel sufficiently contacts the road surface, so that stable traveling can be performed. It is.
[Brief description of the drawings]
FIG. 1 is a perspective view of a reach type forklift.
FIG. 2 is a schematic configuration diagram showing attachment of a lock cylinder.
FIG. 3 is a schematic functional block diagram of a control device.
FIG. 4 is a diagram illustrating a relationship between a pressure in an upper chamber of a lock cylinder and a detection output of a pressure detector.
[Explanation of symbols]
2 Body 7 Drive wheel 15 Control linkage 22 Lock cylinder 35 Control unit 36 Lock valve 37 Pressure detector 38, 39 Oil passage 41 Upper chamber 42 Lower chamber

Claims (2)

A forklift control device comprising: a vehicle body; a wheel provided vertically movable via a suspension mechanism; and a suspension lock device for locking / unlocking the vertical movement of the wheel between the suspension mechanism and the vehicle body,
Detecting means for detecting wheel pressure applied to the wheel;
Control means for unlocking the suspension lock device when the wheel pressure of the wheel detected by the detection means decreases in the locked state of the suspension lock device. Control device. The suspension lock device includes a lock cylinder in which a bottom side is fixed to a vehicle body and a head side is fixed to a suspension mechanism, and a bottom-side oil chamber and a head-side oil chamber are communicated with each other through an oil passage. It consists of a lock valve that opens and closes the oil passage,
The detection means is a pressure detector that measures the pressure in the oil passage between the bottom oil chamber or the bottom oil chamber and the lock cylinder,
The control means operates the lock valve to open the oil passage when the detection output of the pressure detector becomes equal to or less than a predetermined value, thereby bringing the suspension lock device into an unlocked state. The control device for a forklift according to claim 1, wherein:

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