JP2003212498A - Forklift travel control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a load of switching by an operator and prevent an accident due to forgetting of switching by automatically switching an automatic steering travel control and a manual steering travel control. <P>SOLUTION: A sensor 26 for forward moving and a sensor 28 for backward moving for detecting a guidepath wire laid on a travel passage are placed on lower surface of a machine body. Using detected signals of the sensors 26, 28, the automatic steering control is performed by an automatic steering control section 35. When there are no detected signals from the sensors 26, 28, the manual steering travel control is performed by operation of a handle bar 7 at a manual steering control section 24. In accordance with presence of racks detected by rack sensors 42, 43 placed on the machine body, the automatic steering travel control and the manual steering travel control are automatically switched by an automatic switching section 50. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift traveling control device having two functions, an automatic steering traveling function and a manual steering traveling function.

[0002]

2. Description of the Related Art Conventionally, for example, as a forklift truck that enters a traveling path formed between racks that face each other and performs picking work (cargo handling work), for example,
There is one as shown in FIG. This forklift 1
Has a mast device 2 mounted on a vehicle body 3 so as to be able to move up and down, and a driver's cab 4 on which an operator rides and operates the mast device 2 is provided. Further, the cab 4 is provided with a cargo handling tool 5 having a fork that can move in the width direction of the steering wheel 7 and the vehicle body 3 and that can swivel, and can carry in various loads stored in a rack. It is designed to be carried out.

The forklift 1 has two functions, an automatic steering traveling function and a manual steering traveling function. As shown in FIG. 12, in the traveling path 9 between the racks 8, the automatic steering traveling function is used. The steered wheels are automatically steered, and the operator can travel at any speed by only operating the accelerator. Further, the manual steering traveling function is adapted to manually perform steering of the steered wheels and accelerator operation in a place other than the traveling road 9.

A forklift 1 having both the automatic steering traveling function and the manual steering traveling function.
In the cargo handling work of FIG. 12, when the work from the point A to the point B is assumed as shown in FIG. 12, the automatic steering traveling is performed in the portion indicated by the solid arrow in the traveling road 9, and the manual steering traveling is performed in the traveling road 9 It is designed to be performed in the part indicated by the broken arrow other than. Switching between automatic steering traveling and manual steering traveling is performed by the operator operating a changeover switch (not shown) provided in the driver's cab 4 at the points indicated by black circles.

[0005]

However, since the switching operation of the changeover switch between the automatic steering traveling and the manual steering traveling is manually performed,
There is a problem that the operator is burdened and eventually the efficiency of cargo handling work is reduced. There is also a problem that an accident occurs if you forget to switch between automatic steering and manual steering.

The present invention has been provided in view of the above-mentioned problems, and the automatic steering traveling control and the manual steering traveling control are automatically switched, thereby reducing the operator's burden of switching and switching. It is intended to provide a forklift travel control device for the purpose of preventing accidents caused by forgetting.

[0007]

Therefore, in the forklift traveling control device according to the first aspect of the present invention, the operator has a manual steering traveling control in which an accelerator operation of a vehicle speed and a steering wheel steering by a steering wheel operation are performed by an operator, and a vehicle speed. The forklift truck has two functions of automatic steering traveling control in which the operator operates the accelerator and the steering wheels are automatically operated, and when traveling along a rack storing a load, the automatic steering traveling control is performed. In the above, there are provided rack detecting means for detecting the rack, and automatic switching means for automatically switching between the manual steering traveling control and the automatic steering traveling control depending on the presence or absence of a rack detection signal from the rack detecting means. It is characterized by that.

With this structure, when the rack detecting means does not detect the rack, the automatic switching means automatically switches the automatic steering traveling control to the manual steering traveling control, and the rack detecting means detects the rack. When it is detected, the automatic switching means automatically switches from the manual steering traveling control to the automatic steering traveling control. Therefore, the operator alternately switches the automatic steering traveling control and the manual steering traveling control with the changeover switch as in the conventional case. There is no need to switch to
It is possible to reduce the operator's burden of switching and prevent accidents caused by forgetting to turn off.

According to another aspect of the forklift traveling control device of the present invention, the manual steering traveling control is automatically switched to the automatic steering traveling control when the automatic steering traveling control is possible. As a result, the forklift can reliably perform automatic steering traveling control and can smoothly perform cargo handling work.

According to another aspect of the present invention, there is provided a forklift traveling control device, wherein the rack detecting means is composed of a reflective tape attached to a side surface of the rack along a traveling path and a sensor for receiving reflected light from the reflective tape. It is characterized by being configured. Thereby, the rack detecting means can be formed with a simple structure, and the cost can be kept low.

In the traveling control device for a forklift according to claim 4, the rack detecting means is constituted by a magnetic rod laid on the floor surface of the entrance and exit of the rack and a sensor for detecting the magnetism from the magnetic rod. It is characterized by doing. As a result, the rack can be easily detected regardless of the height of the rails that form the rack shelf.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 show the entire structure of the forklift 1, and the same elements as those of the conventional one are designated by the same reference numerals. Note that the cargo handling tool 5 including a fork and the like is omitted in FIG.

1 and 2, the forklift 1
Is a vehicle body 3 provided with steered wheels 18, an outer mast 2A fixed to the vehicle body 3, an inner mast 2B which is movable up and down by a cylinder (not shown) along the inner side of the outer mast 2A, It is composed of a driver's cab 4 which is vertically movable along the inner mast 2B. The steering wheel 1 is attached to the vehicle body 3.
A steering motor 20 for driving the steering wheel 8 and a potentiometer 21 for detecting the steering angle of the steered wheels 18 are continuously provided by gears. Also, supporting the steered wheels 18,
The mount bracket 19 rotatably supported is provided with a disc-shaped steering indicator 23 indicating the direction of the steered wheels 18 via a pivot 22 fixed integrally with the mount bracket 19. This steering indicator 23 allows the current steering angle of the steered wheels 18 to be easily viewed from the driver's cab 4.

Further, the steered wheels 18 are composed of A-phase and B-phase type encoders, and the vehicle speed of the forklift 1 and
A traveling polarity detector S that determines whether the vehicle is traveling forward or backward
Is provided, and the traveling polarity detector S directly detects the movement of the forklift 1 to obtain an accurate traveling polarity. Although not shown, the steered wheels 18 operate as drive wheels driven by a drive motor.

A forward sensor 26 having a plurality of detecting elements for detecting magnetism arranged in the lateral direction is provided at the front and rear of the vehicle body 3.
And a reverse sensor 28 are provided. These sensors 26 and 28 generate an induced voltage due to the magnetic field generated by the induction wire 11 in which an alternating current laid on the ground flows, and detect the induced voltage. Which of the plurality of detection elements is the strongest induction wire. Whether the vehicle body 3 is displaced to the left or right is detected depending on whether 11 is detected. The forward movement sensor 26 is arranged on the arm 25 formed so as to extend from the vehicle body 3. Although the sensors 26 and 28 are magnetic sensors, a pickup coil or an optical sensor for detecting magnetism may be used.

As shown in FIG. 3, the guide wire 11 is laid along the longitudinal direction at a substantially central portion of the traveling path 9 between the racks 8 so that automatic steering traveling can be performed in the traveling path 9. ing. As another example of the guide wire 11, a magnetic tape or a reflective tape made of a material having a high reflectance may be used.

Further, the steering indicator 23
A knob 23A is provided on the upper surface of the steering wheel 18, and the steering wheel 18 can be steered by manually rotating the knob 23A in an emergency when the steering device fails.

Further, the driver's cab 4 is provided with a rotatable handle 7 for outputting a signal for steering the steered wheels 18, an indicator lamp 34 described later, and an accelerator 31. A potentiometer 13 for electrically detecting the steering angle of the handle 7 is attached to the handle 7, and the handle 7 can be rotated with a slight force for rotating the potentiometer 13. . In the present embodiment, the forklift 1 is used in which the steering wheel 7 and the steered wheels 18 are always mechanically separated.

Further, since the driver's cab 4 moves vertically with respect to the vehicle body 3, electric signals are exchanged between the two using a flexible signal line 16. The signal line 16 includes a pulley 14 provided on the lower portion of the driver's cab 4, a pulley 15 provided on the upper portion of the inner mast 2B, and a vehicle body 3.
The pulley 17 provided on the vehicle is sequentially suspended so that the driver's cab 4 can be connected to the vehicle body 3 and the relative distance between the two can be dealt with. The signal line 16
For this, a digital communication type such as an optical fiber may be used, and in this case, communication becomes possible by attaching an optical signal converter or the like.

A forward rack sensor 42 and a backward rack sensor 43 for recognizing that the forklift 1 has entered the traveling path 9 are provided at the front and rear of one side surface of the vehicle body 3 of the forklift 1, respectively. Has been. The forward rack sensor 42 and the backward rack sensor 43 are
For example, it is composed of a light projector and a light receiver and is composed of an optical sensor. Then, as shown in FIG. 4, the reflection tape 46 is attached to the outer surface of the crosspiece 45 that is bridged between the columns 44 that construct the rack 8 over the entire length of the rack 8, and the forward rack sensor 42 and the backward rack sensor 42 are used. By detecting the light emitted from the rack sensor 43 and the light reflected from the reflection tape 46, it is possible to detect whether or not the forklift 1 is located in the traveling path 9. Since the vertical position of the crosspiece 45 to which the reflection tape 46 is attached varies depending on the type of load to be stored, the forward rack sensor 42 and the reverse rack sensor 43 can be arranged at arbitrary positions on the vehicle body 3. As described above, for example, it is a preferable example to make it detachable with a magnet or the like.

Next, the operation will be described with reference to FIG. 5, which is an electrical block diagram of this embodiment. The respective detection signals of the potentiometer 13 that detects the steering angle of the steering wheel 7 and the potentiometer 21 that detects the steering angle of the steered wheels 18 are input to the manual steering control unit 24. The manual steering controller 24 outputs a manual control signal M to the motor controller 37 based on both signals from the potentiometers 13 and 21, and the motor controller 37 drives the steering motor 20 based on the manual control signal M. The steered wheels 18 are steered.

The detection signals from the sensors 26 and 28 for forward and reverse movements of the forklift 1 are input to the automatic steering control section 35, and the signal from the accelerator 31 and the traveling polarity detector S of the traveling polarity detector S are detected. A vehicle speed signal, a traveling polarity signal indicating whether the vehicle is moving forward or backward, and an automatic switching unit 50 described later.
Signals are input to the automatic steering control unit 35, and the automatic control signal A is output to the motor control unit 37 by these signal inputs. Further, the detection signals of the forward and backward sensors 26, 28 are input to the guide wire detection unit 33, the guide wire detection unit 33 receives the traveling polarity signal of the traveling polarity detector S, and the signals are forwarded. If it is a signal, the signal from the forward sensor 26 is selected, and if it is a backward signal, the signal from the backward sensor 28 is selected to perform automatic steering traveling control.

Further, the guide wire detecting section 33 detects the forward movement sensor 26 or the backward movement sensor when the detection values of the forward movement sensor 26 or the backward movement sensor 28 selected above are larger than a predetermined threshold value. When it is determined that the guide wire 11 is present in the switch 28, an H level signal is output to the switching circuit 36, for example.

Next, the structure and operation of the automatic switching section 50 will be described. As shown in FIG. 5, the detection signals from the forward movement sensor 26 and the reverse movement sensor 28 and the detection signals from the forward movement rack sensor 42 and the reverse movement rack sensor 43 are input to the automatic switching section 50, respectively. There is. Then, from the automatic switching unit 50, the indicator light 34 for displaying the automatic steering traveling state or the manual steering traveling state, the switching circuit 36, and the manual steering control unit 2
The signal is output to 4.

FIG. 6 shows a specific circuit diagram of the automatic switching section 50. The signal from the forward movement sensor 26 and the guide wire detecting section 3 are shown.
The forward signal (H level) from the No. 3 is input to the AND gate G2, and the output of the AND gate G2 and the signal from the forward rack sensor 42 are input to the AND gate G1. Further, the signal from the reverse sensor 28 and the reverse signal (H level) from the guide wire detection unit 33 are the AND gate G.
3 and the output from the AND gate G3 and the signal from the reverse rack sensor 43 are input to the AND gate G4.
Has been entered in. Further, the outputs of the AND gates G1 and G4 are input to the OR gate G5, respectively.

When the output of the OR gate G5 is at the H level, that is, when either of the outputs of the AND gate G1 and the AND gate G4 is at the H level, the automatic steering control section 35 and the switching circuit 36 serve as the automatic control selection signal.
Sent to. At the same time, a lamp or a light emitting diode on the "automatic" side of the indicator light 34 is turned on to inform the operator that the vehicle is in the automatic steering traveling state. Further, when the output of the AND gate G1 or the AND gate G4 is L level, the output of the OR gate G5 also becomes L level, and the L level output of this OR gate G5 is inverted by the inverter gate G7 and becomes H level, and the manual control selection signal To the manual steering controller 24,
At the same time, the output of the inverter gate G6 is set to H level to turn on the "manual" side of the indicator lamp 34 to inform the operator that the vehicle is in the manual steering traveling state.

In FIG. 5, the switching circuit 36 automatically steers the motor control unit 37 to the motor control unit 37 according to the AND condition between the H level signal of the guide wire detection unit 33 and the automatic control selection signal (see FIG. 6) from the automatic switching unit 50. The switching signal C for control is output. As a result, the motor control unit 37 resets the manual control signal M from the manual steering control unit 24,
The steered wheels 18 are steered along the guide wire 11 based on the automatic control signal A from the automatic steering control unit 35.

On the contrary, when switching from the automatic steering control unit 35 to the manual steering control unit 24, the L level automatic control selection signal from the automatic switching unit 50 is input, and the H level signal from the automatic switching unit 50 is input. When the vehicle speed signal input from the manual steering control unit 24 and the traveling polarity detector S is equal to or lower than a predetermined speed, the switching circuit 36 causes
A switching signal C that permits this switching is output. In addition,
Since the switching is permitted 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 traveling control, the forklift 1 is steep at a high speed. It is possible to prevent turning.

FIG. 7 shows a specific circuit diagram of the manual steering control section 24. The manual steering control section 24 is composed of a differential amplifier 40, a pulse generator 39, and a polarity discriminator 38. There is. 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 output signal of the differential amplifier 40 is the pulse generator 39 and the polarity discriminator 3
8, and the polarity discriminator 38 is a kind of comparator that discriminates the polarity of the signal of the differential amplifier 40.
That is, at the output end of the polarity discriminator 38, a logical level according to the rotation direction (normal rotation, reverse rotation) for driving the steering motor 20 is generated.

The motor control unit 37 is driven by the output signal from the manual steering control unit 24 configured as described above. The motor control unit 37 includes a transistor, a thyristor and an FET (field effect transistor). The switching elements CH1 to CH4 are configured in a bridge shape so as to change the polarity of the steering motor 20. That is, by turning on the switching elements that are diagonal to each other, a current is passed through the steering motor 20 with a predetermined polarity.

While the steering wheel 20 is driven by 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 in the manual steering traveling state, the driving operation of the forklift 1 is controlled by the accelerator 31 and the steering operation is performed by the driver.
The steered wheels 18 are steered based on the rotation of the steering wheel. As a result, in a place other than the traveling path 9 between the racks 8, the function similar to that of a normal forklift is achieved.

When the automatic steering control unit 35 is selected by the automatic switching unit 50, the automatic steering control unit 35, as is well known, moves from the forward / backward forward movement sensor 26 and the backward movement sensor 28 to the vehicle body 3. A deviation with respect to the guide wire 11 is calculated by a differential amplifier or the like, and the steering motor 20 is controlled so as to eliminate this deviation, whereby forward or backward automatic steering traveling is performed. In this way, the forklift 1 is controlled during the automatic steering traveling control.
The driving motor is controlled based on the accelerator 31 of the operator while the steering operation is completely independent of the steering wheel 7 of the driver's cab 4.
The steered wheels 18 are steered by the induced voltage based on, and it is possible to smoothly enter and travel in the narrow traveling path 9 along the guide line 11 laid in the traveling path 9.

Next, a control operation for automatically switching between the automatic steering traveling function and the manual steering traveling function in traveling of the forklift 1 will be described. First,
Since the guide wire 11 is not laid in a state where the forklift 1 is directed from the predetermined location to the rack 8, the sensors 26 and 28 do not detect the magnetic field, and the forward rack sensor 42 and the backward rack sensor 43 are provided. Since the reflected light is not received, the outputs of the AND gates G1 to G4 shown in FIG. 6 are at the L level. Therefore, the output of the OR gate G5 becomes L level, the output of the inverter gate G6 becomes H level, the indicator lamp 34 lights up the "manual" state, and the output of the inverter gate G7 becomes H level for manual control. The selection signal is output to the manual steering control unit 24. As a result, the operator sees the indicator light 34 and finds that the vehicle is in the manual steering traveling state (traveling possible state), and carries out normal manual driving.

When the forklift 1 is operated to advance manually in the traveling path 9 between the racks 8 as shown in FIG. 8A, first, the forward movement sensor 26 detects the magnetic field from the guide wire 11. To detect. As a result, it can be determined that the forklift 1 is capable of automatic steering traveling.
Further, the guide wire detection unit 33 shown in FIG.
In the case of traveling forward by discriminating the traveling polarity from, the output to the AND gate G2 side is set to H level, the output to the AND gate G3 side is set to L level, and the output of the AND gate G4 is set to L level. The output of the guide wire detection unit 33 is "forward"
Therefore, the output on the "reverse" side is at the L level, and therefore the outputs of the AND gates G3 and G4 are at the L level. In this state, the output of the AND gate G2 is at the H level, but since the H level detection signal from the forward rack sensor 42 is not output, the output of the AND gate G1 remains at the L level.

When the operator manually enters the vehicle body 3 into the traveling path 9, the light projected from the forward rack sensor 42 is reflected by the reflection tape 46 of the rack 8 and is received by the light receiver. The received light signal is input as H level from the forward rack sensor 42 to the AND gate G1, and the output of the AND gate G1 becomes H level. And Gate G
When the output of 1 becomes the H level, the output of the OR gate G5 also becomes the H level, an automatic control selection signal is sent from the automatic switching section 50 to the automatic steering control section 35, and at the same time, "automatic" of the indicator lamp 34 is turned on. In addition, OR gate G5
When the output of the control signal H becomes H level, the manual control selection signal becomes L level by the inverter gate G7, the operation of the manual steering control unit 24 is stopped, and at the same time, "manual" of the indicator light 34 is turned off by the inverter gate G6.

This state is automatic steering traveling,
As shown in FIG. 8A, in the traveling path 9, the operator only performs speed driving by the accelerator 31, and the steered wheels 18 are automatically steered by the automatic steering control unit 35. Then, when carrying in and carrying out a load on the rack 8 and leaving the vehicle body 3 from the traveling path 9 as it is, the forward rack sensor 42 comes off the reflection tape 46 as shown in FIG. 8B. The reflected light cannot be received. Therefore, the signal from the forward rack sensor 42 shown in FIG. 6 becomes L level, and the output of the AND gate G1 becomes L level.

When the output of the AND gate G1 is inverted to L level, the automatic control selection signal is also set to L level, the automatic steering control section 35 is in the non-controlled state, and at the same time, the output of the inverter gate G7 is inverted to H level. A manual control selection signal is sent to the manual steering control unit 24 to enter the manual steering traveling state. Further, the indicator lamp 34 is also inverted by the inverter gate G6 to light "manual". As a result, when the forklift 1 comes out of the traveling path 9, the operator automatically shifts from the automatic steering traveling to the manual steering traveling without operating the changeover switch to switch from the automatic steering traveling to the manual steering traveling as in the conventional case. It can be switched, and normal operation can be performed as it is. Also, when switching from the manual steering travel to the automatic steering travel by going out of the travel path 9, the vehicle body 3 is advanced into the travel path 9 so that the manual steering travel automatically changes to the automatic steering travel as described above. You can switch to.

FIG. 9 shows the case where the forklift 1 is moved backward to enter the traveling road 9, and when the vehicle body 3 is outside the traveling road 9, the manual steering traveling state is performed as described above. When the vehicle body 3 moves backward and enters the traveling path 9, the backward movement sensor 28 detects the magnetic field of the guide wire 11 and the H level detection signal is input to the AND gate G3. Further, the guide wire detection unit 33 inputs the H level signal indicating that the vehicle is in reverse by the polarity determination from the traveling polarity detector S to the AND gate G3, so that the output of the AND gate G3 becomes H level. Since the "forward" signal from the guide wire detection unit 33 is at L level, the outputs of the AND gates G2 and G1 are at L level.

When the forklift 1 further advances into the traveling path 9 and enters, the light projected from the reverse rack sensor 43 is reflected by the reflection tape 46 attached to the rack 8, and the reflected light is reflected. Since the light is received by the light receiver, the backward rack sensor 43 outputs an H level signal and inputs the signal to the AND gate G4. This allows AND gate G
4 output goes to H level and OR gate G5 output goes to H level.
After being inverted to the level, an H level automatic control selection signal is sent to the automatic steering control unit 35 to perform automatic steering traveling. At the same time, the output of the inverter gate G7 is inverted to the L level, so that the manual steering control unit 24 becomes non-controlled. The output of the inverter gate G6 is also H
Invert to the level to turn off "manual" and turn on "automatic" of the indicator light 34.

Further, the vehicle body 3 is driven in a reverse direction, as shown in FIG.
As shown in (b), when the reverse drive rack sensor 43 deviates from the position of the reflection tape 46, the reflected light from the reflection tape 46 cannot be received, so that the output of the reverse movement rack sensor 43 becomes L level, and the AND gate G4. Output also goes low. As a result, the output of the OR gate G5 is inverted to the L level, the automatic control selection signal sent to the automatic steering control unit 35 is set to the L level, and at the same time, the inverter gate G7.
When the output of the above is inverted to the H level, the H level manual control selection signal is sent to the manual steering control unit 24, and the manual steering traveling is performed. Further, the output of the OR gate G5 is inverted to the L level, so that the indicator light 34 is "automatic".
Turn off and turn on "Manual".

As described above, in this embodiment, when the cargo handling work is performed by successively entering and leaving each of the traveling paths 9 shown in FIG. 3, a manual operation in a place other than the traveling path 9 and in the traveling path 9 is performed. Mutual switching between the steering traveling control and the automatic steering traveling control can be automatically performed without the operator performing the switching operation. Therefore, the operator's burden of switching can be reduced, and an accident due to forgetting to switch can be prevented.

By the way, the automatic switching section 50 is not limited to that shown in FIG. 6, and the present invention can be applied to other circuit configurations. For example, automatic switching between automatic steering and manual steering is
Without using the forward movement sensor 26 and the backward movement sensor 28, the forward movement rack sensor 42, the backward movement rack sensor 43,
You may make it use the guide wire detection part 33 which outputs the signal of polarity determination of "forward" and "reverse". in this case,
The AND gates G2 and G3 can be eliminated. However, if the automatic steering traveling control and the manual steering traveling control are automatically switched according to the detection signals of the sensors 26 and 28, the forklift 1 can be surely controlled along the guide wire 11. This is a preferable example from the viewpoint of safety as well.

A forward rack sensor 42 and a backward rack sensor 43 are provided as sensors for detecting the rack 8.
Although only one rack sensor is attached to the center of the side surface of the vehicle body 3, automatic steering traveling and manual steering traveling may be automatically switched.

Further, instead of the forward rack sensor 42 and the backward rack sensor 43, magnetic rods are laid on the floor surfaces of the two entrances and exits of the traveling path 9, and sensors for detecting these magnetic rods are used as the vehicle body 3 The automatic steering traveling and the manual steering traveling may be automatically switched by providing the lower surface of the vehicle. When the rack 8 is detected by the rack sensors 42 and 43 and the reflection tape 46, the structure can be simplified and the cost can be reduced, but the rack 45 of the rack 8 to which the reflection tape 46 is attached has a high height. May be affected by However, since the detection of the rack 8 by the magnetic rod laid on the floor is not related to the height of the crosspiece 45, it is a preferable example in the case of the rack 8 in which a plurality of shelves with different heights of the crosspiece 45 exist.

In this embodiment, the handle 7 of the forklift 1 and the steered wheels 18 are mechanically separated. However, the invention is not limited to this, and the both may be mechanically coupled. In this case, as shown in FIG. 10, the torque sensor T for detecting the relative twist angle between the steering wheel 7 and the steered wheels 18 is mechanically coupled (shown by the broken line).
An electromagnetic clutch MC that mechanically connects and disconnects S with the steering wheel 7 and the steering wheel 18 is provided.

In the manual steering traveling control, the 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 of driving the steering motor 20, the steering wheel 7 is operated with a slight force. It performs a well-known power steering function that can be steered.

Next, when the automatic switching section 50 switches to the automatic steering traveling control, the switching circuit 36 outputs a signal for releasing the electromagnetic clutch MC. This allows
During automatic steering travel control, this electromagnetic clutch MC
By turning off the steering wheel 18, even if the steering wheel 18 is steered by the automatic steering control unit 35, the handle 7 does not rotate, and it is possible to prevent kickback from acting.

[0048]

According to the traveling control device for a forklift according to claim 1 of the present invention, when the rack detecting means does not detect the rack, the automatic switching means automatically changes the automatic steering traveling control to the manual steering traveling control. When the rack detecting means detects a rack, the automatic switching means automatically switches from the manual steering traveling control to the automatic steering traveling control.
Therefore, it is not necessary for the operator to alternately switch between the automatic steering traveling control and the manual steering traveling control with the changeover switch as in the conventional case, the operator's burden of switching can be reduced, and an accident due to forgetting to turn off can be prevented.

According to the forklift traveling control device of the second aspect, when the automatic steering traveling control is possible, the manual steering traveling control is automatically switched to the automatic steering traveling control. The automatic steering traveling control can be reliably performed, and the cargo handling work can be smoothly performed.

According to another aspect of the forklift traveling control device of the present invention, the rack is detected by the reflective tape attached to the side surface of the rack along the traveling path, and the sensor for receiving the reflected light from the reflective tape. Since the means is configured, the rack detecting means can be formed with a simple structure, and the cost can be kept low.

According to another aspect of the forklift traveling control device of the present invention, the rack detecting means includes a magnetic rod laid on the floor surface of the entrance and exit of the rack and a sensor for detecting the magnetism from the magnetic rod. Since,
The rack can be easily detected regardless of the height of the rails that make up the rack shelf.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a forklift according to an embodiment of the present invention.

FIG. 2 is a schematic side view of the forklift according to the embodiment of the present invention.

FIG. 3 is a diagram showing a laid state of guide wires in a traveling path between racks according to the embodiment of the present invention.

FIG. 4 is a diagram showing a state in which a reflection tape is attached to a rail of a rack according to the embodiment of the present invention.

FIG. 5 is an electrical block diagram in the embodiment of the present invention.

FIG. 6 is a block circuit diagram showing a specific circuit of the automatic switching unit according to the embodiment of the present invention.

FIG. 7 is a block circuit diagram of a manual steering control unit in the embodiment of the present invention.

8A and 8B are explanatory diagrams when the forklift according to the embodiment of the present invention travels forward on a traveling path.

9 (a) and 9 (b) are explanatory views when the forklift according to the embodiment of the present invention travels backward on a travel path.

FIG. 10 is an electric block diagram when the steering wheel and the steered wheels are mechanically coupled to each other in the embodiment of the present invention.

FIG. 11 is a perspective view of a forklift truck.

FIG. 12 is an explanatory diagram when switching between automatic steering traveling and manual steering traveling in the conventional cargo handling work.

[Explanation of symbols]

1 forklift 7 handle 8 racks 9 roads 11 guide wire 18 steering wheels 24 Manual steering control unit 26 Forward sensor 28 Reverse sensor 31 accelerator 35 Automatic steering controller 42 Forward rack sensor 43 Reverse rack sensor 46 reflective tape 50 Automatic switching unit

Claims (4)

[Claims] Claims: 1. An automatic steering control system, in which an operator controls a vehicle speed by operating an accelerator and a steering wheel to steer the steered wheels, and an operator controls a vehicle speed by automatically operating the steering wheel. In a forklift that has two functions and performs automatic steering traveling control when traveling along a rack that stores loads, rack detecting means for detecting the rack and a rack detecting signal from the rack detecting means. A forklift traveling control device, comprising: automatic switching means for automatically switching between the manual steering traveling control and the automatic steering traveling control depending on the presence or absence of the above. 2. The forklift traveling control device according to claim 1, wherein when the automatic steering traveling control is possible, the manual steering traveling control is automatically switched to the automatic steering traveling control. . 3. The rack detecting means is constituted by a reflective tape attached to a side surface of the rack along a traveling path, and a sensor for receiving reflected light from the reflective tape. The traveling control device for a forklift according to claim 1 or 2. 4. The rack detecting means is constituted by a magnetic rod laid on a floor surface of an entrance and exit to and from the rack, and a sensor for detecting magnetism from the magnetic rod. The traveling control device for a forklift according to claim 1 or claim 2.