JP2003238098A - Fork lift truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To support an operator's body simultaneously with the operation of a switch separately provided to change over to automatic steering travel control by providing the separate switch besides a changeover switch, and by setting the operation of both switches as a changeover condition to the automatic steering travel control, in changing over to the automatic steering travel control from the manual steering travel control. <P>SOLUTION: A grip is disposed near a steering wheel of a driver's cab, and the grip is provided with a touch sensor 53. In the case of changing over to automatic steering travel control from manual steering travel control, the operator operates the changeover switch 50 and takes hold of the grip with the hand which was holding the steering wheel up to that time. Then the touch sensor 53 is turned on to shift to the automatic steering travel control. At the same time, the operator can support his or her body because of holding the grip. <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 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. 9, the forklift 1 is laid on the floor in the traveling path 9 between the racks 8. The steered wheels are automatically steered by the automatic steering traveling function of traveling while detecting the guiding line 11 that is running, and the operator can travel at any speed by only operating the accelerator. Further, the manual steering traveling function allows an operator to manually steer the steered wheels and operate the accelerator in a place other than the traveling road 9.

In the forklift 1 having the automatic steering traveling function and the manual steering traveling function,
The steering wheel device for driving and operating and the steering device that directly controls the steered wheels are mechanically separated at all times and connected by an electric output signal line. There are two types of mechanical link type in which a steering device and a steering device are linked. During automatic steering travel control, the handle is always free in the case of the electric link type, and in the case of the mechanical link type, the handle is free by releasing the electromagnetic clutch provided midway.

The reason for freeing the steering wheel during the automatic steering traveling control is that when the steering wheel is moved (rotated) in conjunction with the steered wheels during the automatic steering traveling,
This is because there is a risk of the operator's hand being caught in the handle. As described above, conventionally, even when the steering wheel device and the steered wheel device are linked by an electric link type or a mechanical link type, the steering wheel is in a free state during the automatic steering traveling and is in a state of lightly rotating. ing.

[0006]

However, since the handle is designed to be gripped by the left hand so that the operator can support the body while traveling, there is a problem that the handle becomes unstable and it is difficult to support the operator. . Further, when switching from the automatic steering traveling control to the manual steering traveling control, it is necessary to connect the electromagnetic clutch in the mechanical link type under the condition that the positions of the steered wheels and the steering wheel are both neutral. The steered wheels are neutral in the automatic steering traveling control, but the steering wheel is in a free state, so that the steering wheel is set to neutral while watching the neutral lamp provided on the driver's cab 4 side, and the steering wheel is switched to manual. Since the handle is a multi-turn type, it is necessary to rotate the handle many times to find the neutral, which is surprisingly difficult and troublesome to find.
In addition, the electric link type does not require a device such as an electromagnetic clutch, but when it is switched to manual, the steered wheels try to fit the current position of the steering wheel all at once, so the steered wheels turn sharply and the running is unstable. There is also the problem of becoming.

The operator manually operates a changeover switch provided on the driver's cab 4 to switch between the automatic steering traveling control and the manual steering traveling control. Therefore, when the changeover switch is operated to switch from the manual steering travel control to the automatic steering travel control, the steering wheel immediately becomes free, making it difficult for the operator to support his / her body.
There was a problem that it was difficult to operate.

The present invention has been provided in view of the above-mentioned problems. When the manual steering traveling control is switched to the automatic steering traveling control, a separate switch is provided in addition to the changeover switch, and the operation of these switches is performed. (EN) A forklift intended to support the operator's body at the same time as operating a switch separately provided to switch to the automatic steering travel control, as a condition for switching to the automatic steering travel control.

[0009]

Therefore, in the forklift according to claim 1 of the present invention, the steered wheels are automatically steered and the operator operates the accelerator only to operate the accelerator and the steered wheels. In a forklift having a changeover switch for switching a steering wheel operation performed by an operator to a manual steering traveling function, a switch is separately provided as a condition for switching from the manual steering traveling control to the automatic steering traveling control.

With such a configuration, when the manual steering traveling control is switched to the automatic steering traveling control, both the changeover switch and the separately provided switch are operated, and the switching to the automatic steering traveling control is performed. Since the operation is performed twice, the operator can recognize that the current control is the automatic steering traveling control, and only the accelerator operation can be performed, and the traveling control and the cargo handling work can be surely performed.

The forklift according to a second aspect of the invention is characterized in that the switch comprises a touch sensor, and the touch sensor is provided in a grip provided in the vicinity of the handle. As a result, the changeover switch is switched to the automatic steering travel control side, and the operator grips the grip to turn on the touch sensor as a condition for switching to the automatic steering travel control. Then, the operator is in a state in which the hand is separated from the handle and grasps the grip. Therefore, even if the steering wheel is switched to automatic steering control and the steering wheel is in a free state, the hand that previously held the steering wheel holds the grip, so the hand is not caught in the steering wheel and the grip is gripped at the same time. This allows the operator to support his body with the grip. In addition, the operator holds the grip and supports the body, which also contributes to a safe driving operation. Also, when the automatic steering travel control is switched to the manual steering travel control, the operator does not have the handle and is still holding the grip, so the handle maintains the neutral position. Does not have to be adjusted to the neutral point one by one, the return to the manual steering traveling can be accelerated, and the work efficiency can be improved.

[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 an electric link type forklift 1 in which a steering wheel device and a steering wheel device are always mechanically separated from each other, and the same elements as in the related art are denoted 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. 9, 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, on the cab 4, a rotatable handle 7 for outputting a signal for steering the steered wheels 18, and a guide wire 11 are detected to switch between automatic steering control and manual steering control. There are provided an indicator light 34 that is turned on when the vehicle is in a state where it is possible to operate, an accelerator 31, and a changeover switch 50 (see FIG. 3) that switches between automatic steering traveling control and manual steering traveling control. Further, as shown in FIG. 5, a substantially U-shaped grip 52 is provided near the handle 7 of the panel 51 of the cab 4, and the surface of the grip 52 has a strip shape as shown in FIG. A plurality of touch sensors 53 (hatched portions in the drawing) are arranged. The touch sensor 53 has a sheet-like shape and accommodates a pair of thin electrode plates inside. Normally, the pair of electrode plates are separated from each other, and when the operator grips the grip 52, the pair of electrode plates come into contact with each other. Then, the signal is output. In this example, the touch sensors 5
3 is provided, but one sheet-shaped touch sensor 5
3 may be arranged around the grip 52.

Here, as shown in FIG. 3, the signal from the changeover switch 50 and the signal from the touch sensor 53 are inputted to the AND gate G1, and the automatic steering traveling control signal from the changeover switch 50 and the operator. When a detection signal from the touch sensor 53 indicating that the user grips the grip 52 is simultaneously input, the condition for switching from the manual steering traveling control to the automatic steering traveling control is set.

Further, the handle 7 has
A potentiometer 13 for electrically detecting the steering angle is attached, and the handle 7 can be rotated by 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, the flexible signal line 16 is used to exchange electric signals between the two. 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.

Next, the operation will be described with reference to FIG. 3, 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 changeover switch 50 provided on the driver's cab 4 is used by the operator to select either the manual steering control section 24 or the automatic steering control section 35. The selection signal from the changeover switch 50 and the output signal of the AND gate G1 which is the AND condition from the touch sensor 53 are output to the automatic steering control unit 35, the manual steering control unit 24, and the switching circuit 36, respectively. .

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 vehicle speed of the traveling polarity detector S are input. A signal, a traveling polarity signal indicating forward or reverse, and a selection signal from the changeover switch 50 are input to the automatic steering control unit 35, and the automatic control signal A is output to the motor control unit 37 by inputting these signals. ing. Further, the detection signals of the forward and reverse sensors 26 and 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 forward signals. If so, the signal from the forward drive sensor 26 is selected, and if it is a reverse drive signal, the signal from the reverse drive sensor 28 is selected to perform automatic steering traveling control.

Further, the guide wire detecting section 33 causes the guide wire to be sent to each sensor 26 or 28 when the detected value of the forward sensor 26 or the backward sensor 28 selected above is larger than a predetermined threshold value. When it is determined that 11 exists, the switching circuit 36 outputs an H level signal, for example.

The switching circuit 36 instructs the motor control section 37 to perform automatic steering control according to the AND condition of the H level signal of the guide wire detecting section 33 and the selection signal of the H level automatic steering traveling control from the AND gate G1. The switching signal C is output. As a result, the motor controller 37
The manual control signal M from the manual steering control unit 24 is reset, and 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 section 35 to the manual steering control section 24, the manual steering traveling control is selected by the changeover switch 50 (for example, an L level signal) or the operator from the grip 52. When the L-level signal is output from the touch sensor 53 when the hand is released and the vehicle speed signal from the traveling polarity detector S is equal to or lower than a predetermined speed, the switching circuit 36
Outputs a switching signal C that permits this switching. Since the switching is permitted when the vehicle speed is equal to or lower than a predetermined speed, the steering wheel 7 is not operated during automatic steering traveling control.
Even if there is a large angle difference between the steering wheel 18 and the steered wheels 18, the forklift 1 can be prevented from turning sharply at a high speed.

FIG. 4 shows a specific circuit diagram of the manual steering control section 24. The manual steering control section 24 comprises 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.

Therefore, when the changeover switch 50 is switched to the manual steering control section 24 or when the operator releases the grip 52,
The steering motor 20 is operated by the manual steering control unit 24.
Although the steering wheel 7 and the steered wheels 18 are not mechanically connected to each other in a state in which is driven, the steering angles of the both are controlled to be equal or constant. That is, when the manual steering control unit 24 is in the manual steering traveling state, the drive motor is controlled by the accelerator 31 for the traveling operation of the forklift 1, and the steering wheel 18 is operated for the steering operation based on the rotation operation of the steering wheel 7 by the driver. Is steered. 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.

Further, the changeover switch 50 and the touch sensor 5
When the automatic steering control unit 35 is selected by the H-level signal from the AND gate G1 which has received the signal from the automatic steering control unit 35, the automatic steering control unit 35, as is well known, moves forward and backward by the forward movement sensor 26 and the backward movement sensor. The deviation from the guide sensor 28 with respect to the guide wire 11 of the vehicle body 3 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. As described above, while the automatic steering traveling is being controlled, the driving operation of the forklift 1 is controlled by the drive motor based on the accelerator 31 of the operator.
In the steering operation, the steering wheel 18 is steered by the induced voltage based on the sensors 26 and 28 in a state completely independent of the steering wheel 7 of the driver's cab 4, and the guide wire 11 laid inside the traveling path 9
It is possible to smoothly enter and travel along the narrow traveling path 9 along the.

In particular, when switching from the manual steering traveling control to the automatic steering traveling control, the operator first switches the changeover switch 50 to the automatic steering traveling control side, and then holds the grip 52 with the hand that previously held the handle 7. As a result, the touch sensor 53 is turned on, whereby the output of the AND gate G1 becomes H level, and the automatic steering traveling control is performed. Therefore, since the changeover switch 50 is switched to the automatic steering travel control side and the operator grips the grip 52 to turn on the touch sensor 53 as the switching condition to the automatic steering travel control, the manual steering travel control is switched to the automatic steering travel control. When switching to the traveling control, the operator is in a state of releasing the hand from the handle 7 and gripping the grip 52 at the time when the control is switched to the automatic steering traveling control. Therefore, even if the steering wheel 7 is switched to the automatic steering travel control and the steering wheel 7 is in the free state, the hand that has previously held the steering wheel 7 is gripping the grip 52, and therefore the hand is not caught in the steering wheel 7. By gripping the grip 52 at the same time, the operator can support the body with the grip 52.
In addition, the operator holds the grip 52 to support the body, thereby contributing to the safe driving operation.

When the automatic steering traveling control is switched to the manual steering traveling control, the operator releases the grip 52 or the changeover switch 50 is operated.
Is switched to the manual steering traveling control side.

Further, when the automatic steering travel control is switched to the manual steering travel control, the operator does not have the handle 7 and is still holding the grip 52, so that the handle 7 maintains the neutral state. Unlike the conventional case, it is not necessary to adjust the handle 7 to the neutral point one by one, the return to the manual steering traveling can be accelerated, and the working efficiency can be improved.

Although the handle 7 of the forklift 1 and the steered wheels 18 are mechanically separated in this embodiment, the invention is not limited to this, and the both may be mechanically coupled. . In this case, as shown in FIG. 7, a torque sensor T for detecting a relative twist angle between the steering wheel 7 and the steered wheels 18 is mechanically coupled (shown by a 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, the changeover switch 50 is switched to the automatic steering traveling control and the operator grips the grip 5.
The switching circuit 3 is operated by the H level signal from the AND gate G1 by the signal from the touch sensor 53 when the user grips 2.
6 outputs a signal for releasing the electromagnetic clutch MC. As a result, during automatic steering travel control, even if the steering wheel 18 is steered by the automatic steering control unit 35 by disengaging the electromagnetic clutch MC, the handle 7 is in a free state, but the operator grips the grip 52. It can support your body.

[0038]

According to the forklift according to the first aspect of the present invention, when the manual steering traveling control is switched to the automatic steering traveling control, both the changeover switch and the separately provided switch are operated. The operation for switching to the automatic steering traveling control is performed twice, and the operator can recognize that the current control is the automatic steering traveling control, and only the accelerator operation can be performed, so that the traveling control and the cargo handling work can be surely performed.

According to the forklift of claim 2,
Since the switch is composed of a touch sensor, and the touch sensor is arranged in a grip arranged in the vicinity of the handle, the changeover switch is switched to the automatic steering traveling control side, and the operator grasps the grip to operate the touch sensor. Since turning on is a condition for switching to the automatic steering travel control, at the time of switching to the automatic steering travel control, the operator is in a state in which his / her hand is separated from the steering wheel and grips the grip. Therefore, even if the steering wheel is switched to automatic steering control and the steering wheel is in a free state, the hand that previously held the steering wheel grips the grip, so the hand is not caught in the steering wheel and grips the grip at the same time. This allows the operator to support his body with the grip. In addition, the operator holds the grip and supports the body, which also contributes to a safe driving operation. Also, when the automatic steering travel control is switched to the manual steering travel control, the operator does not have the handle and is still holding the grip, so the handle maintains the neutral position. Does not have to be adjusted to the neutral point one by one, the return to the manual steering traveling can be accelerated, and the work efficiency can be improved.

[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 a forklift according to an embodiment of the present invention.

FIG. 3 is a block diagram of an electric system in the case where the steering wheel and the steered wheels are of an electric link type according to the embodiment of the present invention.

FIG. 4 is a circuit diagram of a manual steering control unit according to the embodiment of the present invention.

FIG. 5 is a diagram showing a main part of a panel of a cab in the embodiment of the present invention.

FIG. 6 is an enlarged side view of the grip provided with the touch sensor according to the embodiment of the present invention.

FIG. 7 is a block diagram of an electric system in the mechanical link type according to the embodiment of the present invention.

FIG. 8 is a perspective view of a forklift.

FIG. 9 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 18 steering wheels 50 Changeover switch 52 grip 53 Touch sensor

Claims (2)

[Claims] 1. A changeover switch for switching between an automatic steering traveling function in which a steering wheel is automatically steered and an operator only operates an accelerator, and a manual steering traveling function in which an operator operates an accelerator and a steering wheel to steer the steering wheel. The forklift according to claim 1, wherein a switch is additionally provided as a condition for switching from the manual steering travel control to the automatic steering travel control. 2. The forklift according to claim 1, wherein the switch comprises a touch sensor, and the touch sensor is provided on a grip provided near a handle.