JPH07206400A - Running control device for forklift - Google Patents

Abstract

PURPOSE:To provide a running control device which is capable of smoothly guiding a forklift to a given running passage. CONSTITUTION:A running control device for a forklift comprises an induction zone detecting tools 26-29 to detect an induction zone laid on a rod surface; an automatic steering control part to output a control signal, by which a steering wheel 18 is controlled so that a forklift 1 is driven along an induction zone by means of detecting signals from the induction zone detecting tools 26-29; and a manual steering control part to steer the steering wheel 18 through operation of a handle mounted on the forklift l. Further, the running control device comprises a change-over switch 32 to select one of an automatic steering control part and the manual steering control part; and a switching means to permit switching from the manual steering control part to the automatic steering control part when the given level or more of detecting signals from the induction zone detecting tools 26-29 is detected and the automatic steering part is selected by the change-over switch 32.

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 Conventionally, there is a forklift shown in FIG. 9 as a forklift that enters a traveling path formed between adjacent shelves and performs a picking operation. In the figure, a forklift 12 has a mast device 2 mounted on a vehicle body 3 so as to be movable up and down, and a driver's cab 4 is mounted on the mast device 2.

On the cab 4, a cargo handling tool 5 having a handle 7 and a fork capable of moving in the width direction of the vehicle body and capable of turning.
Is provided and is configured to be able to handle various loads stored on shelves.

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

[0005]

However, in general,
Since the width W of the traveling path 10 is so narrow that the left and right guide rollers 6, 6 can contact the guide rails 9 with each other, the forklift 1 carrying a load on the cargo handling tool 5 can travel along the traveling path 10 in particular. In order to make it enter smoothly, it requires a skillful handle operation technique, resulting in poor workability.

On the other hand, by providing an induction band on the traveling path 10 and providing the forklift 1 with an automatic steering control device capable of detecting the steering band and controlling the steering, it is considered that no steering wheel operation is required. However, in such a configuration, the safety aspect tends to be emphasized, and as a result of keeping the traveling speed low, the cycle time increases.

The present invention has been devised in view of the above problems, and the workability can be improved by easily guiding the forklift to a traveling path between narrow shelves without requiring the driver to operate the steering wheel with skill. It is an object of the present invention to provide a traveling control device for a forklift truck, which can improve the above-mentioned problems and can solve the above-mentioned problems that the driver can operate.

[0008]

According to the present invention, there is provided an accelerator device for a forklift capable of outputting a drive signal which is operated by a driver and drives driving wheels, 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 steering wheel of the forklift truck along the guidance band to a steering motor by a detection signal of the guidance band detection tool, and a handle provided on the forklift. A manual steering control unit that can steer the steered wheels based on an operation, a changeover switch that can select any one of the automatic steering control unit and the manual steering control unit, and a detection signal of the guide band detection tool are predetermined. When the level or more is detected and the automatic steering control section is selected by the changeover switch, the manual steering control is performed. 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, in the forklift, the steering wheel is steered by the driver's operation of the steering wheel and the driving wheel is driven by the operation of the accelerator, It can travel to a predetermined place at high speed and can carry out 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 guide band detection tool is detected at a predetermined level or more, the automatic steering state is switched. In such an automatic steering state, the driver can perform only the accelerator operation, and the steering operation of the steered wheels can be controlled along the guide band to guide the forklift to a predetermined traveling path.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show the entire configuration of the lift truck 1, and the same components as those of the conventional one are designated by the same reference numerals. In FIG. 2, the cargo handling tool 5 including a fork and the like is omitted.

In the figure, the 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 is composed of a lifting mast 2B and a driver's cab 4 that can move up and down along the lifting mast 2B.

A steering motor 20 capable of steering the steered wheels 18 and a potentiometer 21 capable of detecting the steering angle of the steering theory 18 are continuously provided on the vehicle body 3 by gears. Further, a mount bracket 19 supporting the steered wheels 18 and rotatably supported is provided with a disc-shaped steering indicator 23 indicating the direction of the steered wheels 18 via a pivot 22 integrally fixed thereto. The current steering angle of the steered wheels 18 is configured to be easily visible from the cab 4.

Further, the steered wheels 18 include A-phase and B-phase type encoders, and a traveling polarity detector S capable of discriminating the vehicle speed of the forklift 1 and the traveling polarity of forward or reverse.
By providing the forklift truck and detecting the movement of the forklift directly, an accurate traveling polarity is obtained.

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

Further, a pair of forward-moving pickup coils 2 as guide band detecting tools are provided on the front and rear of the vehicle body 3, respectively.
6, 27 and pickup coils 28, 29 for the reverse drive are provided. The pickup coils 26 to 29 are well-known ones that generate an induced voltage due to the magnetic field generated by the induction wire 11 laid on the ground and through which an alternating current flows, and detect such voltage. The forward pickup coils 26, 27
Is attached to an arm 25 extending from the vehicle body 3.

A magnetic sensor, an optical sensor, or the like may be used instead of the pickup coil. Further, in this example, the knob 23A is fixed to the upper surface of the steering indicator 23, and the steering wheel is manually rotated in an emergency such as when the steering device of the present invention fails. You can change the direction of 18.

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, which will be described later, a changeover switch 32, and an accelerator 31, and the handle 7 is provided with the handle 7. Is equipped with a potentiometer 13 capable of electrically detecting the steering angle of the steering wheel 7, and the steering wheel 7 can be rotated by a slight force only for rotating the potentiometer 13.

Thus, in this embodiment, the handle 7
The forklift 1 is used which is mechanically separated from the steered wheels 18 at all times.

Since the cab 4 can move vertically with respect to the vehicle body 3, electric signals can be exchanged between the two using a flexible signal line 16. In this signal line,
A digital communication type such as an optical fiber may be used, and in this case, it becomes possible to communicate by attaching an optical signal converter or the like.

The signal line 16 is sequentially wound around a pulley 14 provided on the lower portion of the driver's cab 4, a pulley 15 provided on the upper portion of the lifting mast 2B, and a pulley 17 provided on the vehicle body 3 so as to be wound around the driver's cab 4. It is possible to connect from the vehicle body to the vehicle body, and it is possible to cope with a change in the relative distance between the two.

In the present embodiment, a guide line is used as the guide band, but other than this, magnetic tape, a reflective tape made of a material having a high reflectance, or the like is used to simplify the construction of the floor surface. sell. Further, the guide wire 11 is linearly laid on a traveling path 10 formed between the shelves 8 ... Installed in the warehouse S as shown in FIG. 5, or the depth end of the warehouse S as shown in FIG. When the gap H from the rack 8 to the end surface of the shelf 8 is small, the guide wire 11 may be laid with an arc portion and a straight portion.

Next, an electrical block diagram of this embodiment is shown in FIG.
It will be explained together with its action based on. The respective detection signals of the potentiometer 13 capable of detecting the steering angle of the steering wheel 7 and the potentiometer 21 capable of detecting the steering angle of the steered wheels 18 are input to the manual steering control unit 24.

The manual steering control section 24 outputs a manual control signal M to the motor control section 37 based on the both input signals. Based on this, the motor control section 37 drives the steering motor 20 to steer the steered wheels 18. It

The changeover switch 32 provided on the cab 4 allows the driver to select either the manual steering control section 24 or the automatic steering control section 35. Part 3
5, the manual steering control unit 24 and the switching circuit 36
Are output respectively.

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

The detection signals of the pickup coils 26 to 29 are output to the guide wire detection circuit 33. The guide wire detection circuit 33 receives the traveling polarity signal of the traveling polarity detector S, adopts the forward pickup coils 26 and 27 if the signal is a forward signal, and the backward pickup coils 28 and 29 if it is a backward signal. Can be adopted to ensure automatic control.

The guide wire detection circuit 33 is composed of a pair of the above-mentioned pair of pick-up coils 26 and 27, or two.
If the detection values of 8 and 29 are larger than the predetermined threshold value, it is determined that an induction wire exists between the pickup coils, and a lighting signal for lighting 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 the guide wire detection circuit 33.
By the AND condition between the "H" level signal of No. 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 the automatic control signal A from the automatic steering control unit 35.
The steering wheel 18 can be steered along the guide line 11 based on

On the contrary, when switching from the automatic steering control section 35 to the manual steering control section 24, the manual steering control section is selected by the changeover switch 32, and
When the vehicle speed signal from the traveling polarity detector S is below a predetermined speed, the switching circuit 36 can output a switching signal C that permits this switching.

In this way, by permitting switching only when the vehicle speed is equal to or lower than the predetermined speed, even if there is a large angle difference between the steering wheel 7 and the steered wheels 18 during the automatic steering control, the high speed can be achieved. Therefore, the forklift 1 can be prevented from turning suddenly.

The manual steering control unit 24 is shown in FIG.
A differential amplifier 40, a pulse generator 39, and
It is composed of a polarity discriminator 38.

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

The output signal of the differential amplifier 40 is input to the pulse generator 39 and the 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, at the output end of the polarity discriminator 38, a logical level is generated according to the rotation direction (normal 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 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 that are diagonal to each other, a current can be passed through 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.

Therefore, when the selector switch 32 is switched to the manual steering control section 24, the steering wheel 7 and the steering wheel 18 are not mechanically connected, but
The steering angles of the two are controlled so as to be equal or constant.

That is, when the manual steering control unit 24 is selected by the changeover switch 32, the forklift 1 is controlled by the drive motor based on the accelerator 31 for the traveling operation and the steering operation is performed by the driver to rotate the steering wheel 7. The steered wheels 18 are steered based on the operation.

As a result, when the forklift 1 is operated in a relatively wide area other than the traveling path between the shelves, the same function as the normal forklift 1 can be achieved.

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

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

As a result, in a place where a skillful driving operation is required, it is possible to improve workability by eliminating the need for the driver to operate the steering wheel 7. Further, since only the steered wheels 18 are steered by the automatic steering control unit 35, even if the driver puts his / her hand on the steering wheel 7, the steering wheel 7 provided on the cab 4 does not rotate. It is possible to prevent the kickback force from acting on the hand.

Further, in the present embodiment, the driver's cab 4 is provided with an indicator light 34 which can be turned on when the detection values of the pickup coils 26 to 29 become larger than the threshold value for automatic steering control. Therefore, the manual steering control can be easily switched to the automatic steering control.

Furthermore, when the guide wire 11 is buried in the ground, it can be provided with a display that can be recognized from the outside. According to this structure, each pickup coil of the forklift 1 is used as a guide wire. It is easy to get closer.

In this example, the handle 7 and the steered wheels 18 of the forklift 1 are mechanically separated, but the invention is not limited to this, and both may be mechanically coupled.

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

However, in the manual steering control, the torque signal detected by the torque sensor TS is input to the manual steering control section 24A.

The manual steering control unit 24A calculates the auxiliary torque based on the input torque signal and outputs this signal M to the motor control unit 37, which drives the steering motor 20 and, as a result, with a slight force. It performs a well-known power steering function capable of steering the steering wheel 7.

Next, when the changeover switch 32 changes over to the automatic steering control section, the changeover circuit 36 outputs a signal for releasing the electromagnetic clutch MC. Thus, during automatic steering control, by disengaging the clutch means, even if the steered wheels 18 are steered by the automatic steering control, the steering wheel 7 does not rotate and kickback is prevented from acting. sell.

[0051]

As described above, the driver selects the automatic steering control section with the changeover switch and positions the forklift along the guide line to operate the steering wheel in a difficult place. The forklift can be steered and smoothly entered into a narrow traveling path, and workability can be improved. Since manual steering is also possible, manual steering by a trained driver can be ensured and versatility can be enhanced, and safety at the time of switching from automatic to manual is enhanced.

[Brief description of drawings]

FIG. 1 is a plan view of a forklift truck.

FIG. 2 is a side view of a forklift truck.

FIG. 3 is an electrical block diagram according to an embodiment of the present invention.

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

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

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

FIG. 7 is an electrical block diagram in another embodiment.

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

FIG. 9 is a perspective view of a forklift truck.

[Explanation of symbols]

 1 forklift 2 mast device 3 vehicle body 4 driver's cab 5 cargo handling tool 6 guide roller 7 handle 8 shelf 10 traveling path 11 guide wire 13 potentiometer 18 steering wheel 20 steering motor 21 potentiometer 24 manual steering control section 26-29 pickup coil 31 accelerator 32 switching Switch 35 Automatic steering control unit 36 Switching circuit 37 Motor control unit

Claims (4)

[Claims] Claim: What is claimed is: 1. An accelerator device, which is operated by a driver and can output drive signals for driving drive wheels, for a forklift, an induction band detection tool for detecting an induction band laid on a road surface, and the induction band detection. An automatic steering control unit that can output a control signal to a steering motor to control the steered wheels so that the forklift follows the guide band by a tool detection signal, and steer the steered wheels based on a steering wheel 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 the detection signal of the guide band detection tool is detected at a predetermined level or higher, and When the automatic steering control section is selected by the changeover switch, the automatic steering control section is operated from the manual steering control section. 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 section to the manual steering control section when the vehicle speed of the forklift is equal to or lower than a predetermined speed and the manual steering braking section is selected by the changeover switch. The travel control device for a forklift according to claim 1, wherein the travel control device is permitted. 3. The guide band detecting tool includes a forward guide band detecting tool and a reverse guide band detecting tool which are provided at a front portion and a rear portion of the forklift, respectively, and the guide belt detecting means is provided in accordance with the forward movement and the reverse movement of the forklift. 3. The traveling control device for a forklift according to claim 1, wherein it is possible to switch between the forward guidance band detection tool and the backward guidance band detection tool. 4. The switching circuit releases the mechanical coupling between the steering wheel and the steered wheels when switching from the manual steering control section to the automatic steering control section. Forklift travel control device.