JP3135184B2 - Travel control device for forklift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control device capable of smoothly guiding a forklift to a predetermined traveling path.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional forklift for performing a picking operation by entering a traveling path formed between adjacent shelves. In the figure, a forklift 12 has a mast device 2 mounted on a vehicle body 3 so as to be able to move up and down, and a cab 4 is mounted on the mast device 2.

The cab 4 has a handle 7 and a cargo handling device 5 having a fork which can move in the width direction of the vehicle body and can pivot.
Is provided, and is configured to be able to handle various loads stored on the shelf.

Guide rollers 6 are mounted on the left and right sides of the vehicle body 3, and as shown in FIG. 8, a forklift is provided along an arc portion 9 A of a guide rail 9 provided around the shelf 8. 12 can be guided to the traveling path 10.

[0005]

However, usually,
The width W of the traveling path 10 is so narrow that the left and right guide rollers 6 can abut on the guide rails 9. Smooth entry requires skillful handle operation techniques and poor workability.

On the other hand, it is conceivable that a steering band is not required at all by providing a guidance band or the like on the traveling path 10 and providing the forklift 1 with an automatic steering control device capable of detecting and controlling the steering. However, in such a configuration, the safety aspect tends to be emphasized, and as a result, the traveling speed is reduced, resulting in an increase in the cycle time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to easily guide a forklift to a traveling path between narrow shelves without requiring a driver's skilled steering operation. It is an object of the present invention to provide a travel control device of a forklift capable of improving the above-mentioned problem and solving the above-mentioned problem that enables the operation by a driver.

[0008]

SUMMARY OF THE INVENTION The present invention provides an accelerator device which can be operated by a driver and outputs a drive signal for driving a drive wheel, and a guide band which can detect a guide band laid on a road surface. A detection tool, an automatic steering control unit capable of outputting a control signal for controlling a steered wheel of the forklift along the guidance band to a steering motor based on a detection signal of the guidance band detection tool, and a handle provided on the forklift A manual steering control unit capable of steering a steered wheel based on an operation, a changeover switch capable of selecting any one of the automatic steering control unit and the manual steering control unit, and a detection signal of the guidance band detection tool being a predetermined signal. When the automatic steering control unit is selected by the changeover switch and the manual steering is detected. A travel control device for a forklift comprising providing a switching means for permitting switching to the automatic steering control unit from the grayed controller.

[0009]

According to the present invention, when the manual steering control section is selected by the changeover switch, the forklift operates the steering wheel by the operation of the steering wheel by the driver and the driving wheel is driven by the operation of the accelerator. The vehicle can travel at a high speed to a predetermined place, and can perform cargo handling work.

On the other hand, when the automatic steering control section is selected by the changeover switch and the detection signal of the guiding band detector is detected at a predetermined level or more, the state is switched to the automatic steering state. In such an automatic steering state, the driver performs only the accelerator operation, and the steering operation of the steered wheels is controlled so as to follow the guidance band, and the forklift can be guided to a predetermined traveling path.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show the overall configuration of the lift truck 1, and the same components as those in the related art are denoted by the same reference numerals. Note that FIG. 2 omits the cargo handling tool 5 composed of a fork or the like.

In FIG. 1, a lift truck 1 can be moved up and down by a vehicle body 3 having steered wheels 18, a fixed mast 2A fixed to the vehicle body 3, and a cylinder (not shown) along the fixed mast 2A. It comprises a lifting mast 2B and a driver's cab 4 that can move up and down along the lifting mast 2B.

The vehicle body 3 is provided with a steering motor 20 that can steer the steered wheels 18 and a potentiometer 21 that can detect the steering angle of the steering theory 18 by gears. The mount bracket 19 which supports the steered wheel 18 and is rotatably supported is provided with a disk-shaped steering indicator 23 indicating the direction of the steered wheel 18 via a pivot 22 integrally fixed thereto. The present steering angle of the steered wheels 18 is configured to be easily visible from the cab 4.

Further, the steering wheel 18 includes an A-phase and a B-phase type encoder, and a traveling polarity detector S which can determine the vehicle speed of the forklift 1 and the traveling polarity of forward or reverse.
To obtain an accurate running polarity by directly detecting the movement of the forklift.

Although not shown, the steered wheels 18 operate as drive wheels driven by a drive motor.

Further, a pair of forward pickup coils 2 as a guide band detector are provided at the front and rear portions of the vehicle body 3, respectively.
6 and 27 and pickup coils 28 and 29 for backward movement are provided. The pickup coils 26 to 29 are well-known in which an induced voltage is generated by a magnetic field generated by an induction wire 11 laid on the ground and through which an alternating current flows, and the voltage is detected. The forward pickup coils 26 and 27
Is mounted on an arm 25 extending from the vehicle body 3.

Incidentally, a magnetic sensor, an optical sensor or the like may be used instead of the pickup coil. In this embodiment, a knob 23A is fixed to the upper surface of the steering indicator 23. In an emergency such as when the steering device of the present invention breaks down, the steering wheel is manually turned to operate the steering wheel 23A. 18 can be turned.

The driver's cab 4 has a rotatable handle 7 capable of outputting a signal for steering the steered wheels 18, an indicator light 34, a changeover switch 32, and an accelerator 31, which will be described later. A potentiometer 13 that can electrically detect the steering angle of the steering wheel 7 is attached, and the steering wheel 7 can be rotated with a small force that only rotates the potentiometer 13.

As described above, in this embodiment, the handle 7 is
The forklift 1 in which the steering wheel 18 is mechanically separated from the steering wheel 18 is always used.

Since the cab 4 can move up and down with respect to the vehicle body 3, transmission and reception of electric signals between the two can be performed using a flexible signal line 16. This signal line
A digital communication type such as an optical fiber may be used, and in this case, communication becomes possible by providing an optical signal converter or the like.

The signal line 16 is sequentially wound around a pulley 14 provided at a lower portion of the cab 4, a pulley 15 provided at an upper portion of the lifting mast 2 B, and a pulley 17 provided at the vehicle body 3. To the vehicle body, and can cope with a change in the relative distance between the two.

In this embodiment, a guide wire is exemplified as a guide band. However, in addition to this, a magnetic tape or a reflective tape made of a material having high reflectivity may be used to simplify construction of a floor surface. sell. The guide wire 11 is, as shown in FIG. 5, linearly laid on a traveling path 10 formed between shelves 8... Installed in the warehouse S, or a depth end of the warehouse S as shown in FIG. When the gap H from the edge to the end face of the shelf 8 is small, the guide wire 11 may be constructed by an arc portion and a straight portion.

Next, an electric block diagram of this embodiment is shown in FIG.
The operation will be described based on the above. The respective detection signals of the potentiometer 13 that can detect the steering angle of the steering wheel 7 and the potentiometer 21 that can detect the steering angle of the steered wheels 18 are input to the manual steering control unit 24.

The manual steering control unit 24 outputs a manual control signal M to the motor control unit 37 based on both input signals, and based on this, the motor control unit 37 drives the steering motor 20 and the steered wheels 18 are steered. You.

The changeover switch 32 provided on the driver's cab 4 allows the driver to select either the manual steering control unit 24 or the automatic steering control unit 35. Part 3
5. The manual steering control unit 24 and the switching circuit 36
Output to

The automatic steering control unit 35 includes an induced voltage of the pickup coils 26 to 29 for forward and backward movement of the vehicle body, a forward or backward signal of the accelerator 31, a selection signal of the changeover switch 32, a traveling polarity detector. The vehicle speed signal of S and the traveling polarity signal of forward or reverse are input and an automatic control signal A is output to the motor control unit 37 according to a predetermined processing procedure.

The detection signals of the respective pickup coils 26 to 29 are output to a guide line detection circuit 33. The guide line detection circuit 33 receives the traveling polarity signal of the traveling polarity detector S, and adopts the forward pickup coils 26 and 27 if the signal is a forward signal, and uses the reverse pickup coils 28 and 29 if the signal is a reverse signal. To ensure automatic control.

The guide wire detecting circuit 33 includes a pair of the pair of pickup coils 26 and 27 employed,
If each of the detected values 8 and 29 is larger than a predetermined threshold value, it is determined that an induction wire exists between the respective pickup coils, and a lighting signal for turning on the indicator lamp 34 is output. At the same time, an “H” level signal is output to the switching circuit 36.

The switching circuit 36 is connected to the induction wire detecting circuit 33.
Of the "H" level signal and the selection signal input of the automatic steering control unit of the changeover switch 32,
A switching signal C for automatic steering control is output to the motor control unit 37. As a result, the motor control unit 37 resets the manual control signal M from the manual steering control unit 24, and resets the automatic control signal A from the automatic steering control unit 35.
, The steered wheels 18 can be steered along the guidance line 11.

Conversely, switching from the automatic steering control unit 35 to the manual steering control unit 24 is performed by selecting the manual steering control unit by the changeover switch 32 and
When the vehicle speed signal from the traveling polarity detector S is lower than a predetermined speed, the switching circuit 36 can output a switching signal C for permitting this switching.

As described above, by permitting the switching only when the vehicle speed is equal to or lower than the predetermined speed, even if a large angle difference occurs between the steering wheel 7 and the steered wheels 18 during the automatic steering control, the high speed is maintained. Thus, the forklift 1 can be prevented from turning sharply.

The manual steering control unit 24 is provided with the configuration shown in FIG.
, A differential amplifier 40, a pulse generator 39,
And a polarity discriminator 38.

The differential amplifier 40 uses the potentiometers 13 and 21 as input signals and outputs a signal proportional to the difference between the two input signals. The gain of the differential amplifier 40 is
This can be performed by changing the value of a resistor (not shown).

The output signal of the differential amplifier 40 is input to a pulse generator 39 and a polarity discriminator 38, respectively.

The polarity discriminator 38 is a kind of comparator for discriminating the polarity of the signal of the differential amplifier 40. That is, the output terminal of the polarity discriminator 38 is configured to generate a logical level corresponding to the rotation direction (forward rotation, reverse rotation) for driving the steering motor 20.

The motor control unit 37 is driven by the output signal from the steering control unit 24 configured as described above. The motor control unit 37 is configured such that the switching elements CH1 to CH4 such as transistors, thyristors, and FETs are configured in a bridge shape so that the polarity of the steering motor 20 can be changed. That is, by turning on the switching elements on diagonal lines with each other, a current can be supplied to the steering motor 20 with a predetermined polarity.

A battery (not shown) mounted on the vehicle body 3 is connected to the steering motor 20.

Accordingly, in a state where the changeover switch 32 is switched to the manual steering control unit 24, although the steering wheel 7 and the steered wheels 18 are not mechanically connected,
The two steering angles are controlled so as to be equal or at a fixed ratio.

That is, when the manual steering control unit 24 is selected by the changeover switch 32, the forklift 1 controls the driving motor for the running operation based on the accelerator 31, and the steering operation of the steering wheel 7 by the driver. The steered wheels 18 are steered based on the operation.

As a result, when the forklift 1 is operated in a relatively wide place other than the running path between the shelves, the same function as the ordinary forklift 1 can be performed.

As is well known, the automatic steering control unit 35 calculates a deviation from the front and rear pickup coils 26 to 29 with respect to the guide wire 11 of the vehicle body 3 by a differential amplifier or the like, and controls the steering motor 20 to eliminate the deviation. I do.

Thus, during automatic steering control,
In the forklift 1, the driving operation of the forklift 1 is controlled based on the accelerator 31, and the steering operation is based on the induced voltage based on the pickup coils 26 to 29 in a state completely independent of the handle 7 provided on the driver's cab 4. As a result, the steered wheels 18 are steered, and can smoothly enter the narrow traveling path 10 along the guide line laid in the traveling path 10.

As a result, in places where the driving operation requires skilled skills, the operation of the steering wheel 7 by the driver is not required at all, and the workability can be improved. Also, since only the steered wheels 18 are steered by the automatic steering control unit 35, even if the driver puts his hand on the steering wheel 7, the steering wheel 7 provided on the cab 4 does not rotate. The kickback force can be prevented from acting on the hand.

In this embodiment, the driver's cab 4 is provided with an indicator light 34 which can be turned on when the detected value of each of the pickup coils 26 to 29 becomes larger than a threshold value at which automatic steering can be controlled. Therefore, switching from manual steering control to automatic steering control can be facilitated.

Further, when the guide wire 11 is buried underground, a display which can be recognized from the outside can be provided. According to this configuration, each pickup coil of the forklift 1 is connected to the guide wire. It is easy to get closer.

In this embodiment, the handle 7 and the steered wheels 18 of the forklift 1 are mechanically separated from each other. However, the present invention is not limited to this.

In this case, as shown in FIG. 7, the mechanical connection between the steering wheel 7 and the steered wheels 18 (shown by broken lines)
A torque sensor TS capable of detecting a relative twist angle between the two,
An electromagnetic clutch MC capable of releasing the mechanical connection between the steering wheel 7 and the steered wheels 18 is provided.

In the manual steering control, a torque signal detected by the torque sensor TS is input to the manual steering control unit 24A.

The manual steering control unit 24A calculates an auxiliary torque based on the input torque signal, and outputs this signal M to the motor control unit 37. As a result, the steering motor 20 is driven. It performs a well-known power steering function capable of steering the steering wheel 7.

Next, when the mode is switched to the automatic steering control section by the changeover switch 32, the switching circuit 36 outputs a signal for releasing the electromagnetic clutch MC. By disengaging the clutch means during the automatic steering control, the steering wheel 7 does not rotate even if the steered wheels 18 are steered by the automatic steering control, thereby preventing kickback from acting. sell.

[0051]

As described above, the driver selects the automatic steering control unit with the changeover switch and positions the forklift along the guide line so that the driver can operate the steering wheel in places where operation is difficult. It is possible to steer a forklift smoothly into a narrow running path and to smoothly enter, thereby improving workability. In addition, since manual steering is also possible, manual steering by a skilled driver can be ensured, general versatility can be improved, and safety at the time of switching from automatic to manual can be enhanced.

[Brief description of the drawings]

FIG. 1 is a plan view of a forklift.

FIG. 2 is a side view of the forklift.

FIG. 3 is an electric block diagram in one embodiment of the present invention.

FIG. 4 is a block diagram of a manual steering control unit.

FIG. 5 is a diagram showing a laying state of a guide wire.

FIG. 6 is a diagram showing a laying state of a guide wire.

FIG. 7 is an electric block diagram according to another embodiment.

FIG. 8 is a plan view for explaining a conventional technique.

FIG. 9 is a perspective view of a forklift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Forklift 2 Mast device 3 Body 4 Driver's cab 5 Cargo handling tool 6 Guide roller 7 Handle 8 Shelf 10 Travel path 11 Guidance line 13 Potentiometer 18 Steering wheel 20 Steering motor 21 Potentiometer 24 Manual steering controller 26-29 Pickup coil 31 Accelerator 32 Switching Switch 35 Automatic steering control unit 36 Switching circuit 37 Motor control unit

Continuation of front page (56) References JP-A-4-129872 (JP, A) JP-A-4-365797 (JP, A) JP-A-61-273499 (JP, A) JP-A-7-138000 (JP, A) JP-A-2-48703 (JP, A) JP-A-59-184918 (JP, A) JP-A-1-312609 (JP, A) Japanese Utility Model Laid-Open No. 51-109514 (JP, U) 49-1825 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B66F 9/24 G05D 1/02

Claims (4)

(57) [Claims] An accelerator device which can be operated by a driver and outputs a drive signal for driving a driving wheel, a guide band detector which can detect a guide band laid on a road surface, and a guide band detection device for detecting a guide band laid on a road surface. An automatic steering control unit capable of outputting a control signal for controlling a steering wheel so that the forklift moves along the guidance band by a tool detection signal to a steering motor, and steering a steering wheel based on a steering operation provided on the forklift. A manual steering control unit, a changeover switch capable of selecting any one of the automatic steering control unit and the manual steering control unit, and a detection signal of the guide band detector is detected at a predetermined level or more, and When the automatic steering control unit is selected by the changeover switch, the automatic steering control is performed by the manual steering control unit. Running control device for a forklift comprising providing a switching means for permitting switching to grayed controller. 2. The switching means switches from the automatic steering control unit to the manual steering control unit when the vehicle speed of the forklift is equal to or lower than a predetermined speed and a manual steering braking unit is selected by the switching switch. 2. The travel control device for a forklift according to claim 1, wherein: 3. The guide band detector includes a forward guide band detector and a reverse guide band detector provided at a front portion and a rear portion of a forklift, respectively. 3. The travel control device for a forklift according to claim 1, wherein the guide band detector for forward movement and the guide band detector for reverse movement can be switched. 4. The switching circuit according to claim 1, wherein the switching circuit releases the mechanical connection between the steering wheel and the steering wheel when switching from the manual steering control unit to the automatic steering control unit. Travel control device for forklift.