JPH11222396A - Forklift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve safety at traveling mode switching time by permitting switching of a mode when a traveling speed of a forklift truck is 0 and a brake is put in an operating stopping braking state by the control part. SOLUTION: The control part permits switching of a mode when a traveling speed of a forklift truck 1 is 0 and a brake is put in an operating stopping braking state. For example, when a traveling mode in switched to an omnidirectional traveling mode (b) from a normal traveling mode (a), the forklift truck 1 is stopped, and the brake is also operated, Steering angle θL, θR of left/right load wheels 4, 5 are steered so as to coincide with a steering angle θD of a drive wheel 6 by setecting the omnidirectional traveling mode (b) by a mode selecting means. Therefore, mode switching in traveling can be prevented since the brake is put in an operating state in a surely stopped state when switching a traveling mode of the forklift truck 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift capable of traveling in a traveling mode selected from a plurality of traveling modes, and more particularly to a forklift capable of improving safety when switching between traveling modes.

[0002]

2. Description of the Related Art
The driver selects an optimal driving mode from among a plurality of driving modes according to the use environment, and the control unit switches to this driving mode, and a forklift capable of performing a parallel movement driving or a turning on the spot is provided. The applicant of the present application has already proposed this in, for example, JP-A-5-116463.

[0003] When the running mode is appropriately switched, it is necessary to change the directions of the wheels so as to follow different control patterns.

According to the present invention, the traveling speed of a forklift is 0
And based on permitting the switching of the mode during the stop braking state in which the brake is applied,
It is an object of the present invention to provide a forklift capable of improving safety when switching between traveling modes.

[0005]

According to a first aspect of the present invention, there is provided a forklift capable of traveling in a traveling mode selected from a plurality of traveling modes, wherein the traveling mode is selectable. Selecting means, and a control unit capable of switching the running mode to the selected running mode in response to a mode signal from the mode selecting means, wherein the controlling unit determines that the running speed of the forklift is 0 and the brake is applied. The forklift is characterized in that the switching of the mode is permitted in a stopped braking state.

According to a second aspect of the present invention, the control unit performs a mode switching process by permitting the switching of the traveling mode, and when the traveling instruction of the forklift is issued when the mode switching is completed, the control unit performs the traveling. 2. The forklift according to claim 1, wherein the travel of the forklift is prohibited until the instruction is temporarily stopped.

According to a third aspect of the present invention, there is provided the forklift according to the first or second aspect, wherein the control unit causes the display unit to display that the driving mode is being switched.

According to a fourth aspect of the present invention, the forklift includes a load wheel supported by each of the left and right straddle arms so as to be steerable, a drive wheel steerable by a steering wheel and rotatably driven; Steering angle detecting means for detecting a steering angle, and the rotation axis of the road wheel is fixed so as not to be steerable at a position along the vehicle width direction, and the direction of the vehicle body is steered by steering the drive wheel. 4. The vehicle according to claim 1, wherein the vehicle is driven in a plurality of driving modes including a normal driving mode that can be changed and at least one or more special driving modes other than the normal driving mode. A forklift according to any one of the preceding claims.

According to a fifth aspect of the present invention, in the special running mode, the vehicle can be moved without changing the direction of the vehicle body by making the steering angle of the drive wheel substantially equal to the steering angle of the left and right road wheels. 5. The forklift according to claim 4, including a parallel traveling mode and a turning mode in which the vehicle body turns with a substantially minimum turning radius.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. The forklift of the present embodiment includes:
A forklift capable of traveling in a traveling mode selected from among a plurality of traveling modes is assumed.

In this embodiment, as shown in FIG. 1, a reach-type forklift 1 is illustrated, and is attached to left and right straddle arms 3L, 3R projecting forward from a vehicle body 2 so as to control the steering angle. Steerable left and right road wheels 4, 5; a drive wheel 6 provided on the vehicle body 2 and steerable with a handle H; moving back and forth along the straddle arms 3L, 3R; And a mast device M having a fork F as a cargo handling device.

The left and right road wheels 4, 5 are supported by turning gear cases 8B, 8C, respectively.
Servo motors 9L and 9R are linked to these turning gear cases 8B and 8C via conductive members 7 such as belts. Therefore, each of the left and right road wheels 4, 5
By driving the servo motors 9L and 9R, the steering angles can be individually controlled and their positions can be maintained. In this example, the road wheels 4 and 5 are steered around center positions L and R in the width and circumferential directions of the wheels.

The drive wheel 6 includes an electric motor M
(Not shown). This drive wheel 6
Is driven by an accelerator device 20 provided in the driver's seat.
Can be adjusted. In the present embodiment, an example in which a speed sensor 22 that can detect the traveling speed of the forklift 1 is provided on the rotation shaft of the drive wheel 6 is illustrated. Note that the speed sensor 22 can be provided at another position.

The drive wheel 6 is pivotally supported by a turning gear case 8A. By operating a handle H, the turning gear case 8A is steered. It should be noted that a so-called fly-by-wire system in which the drive wheel is mechanically separated from the steering wheel H may be employed as the steering mechanism.

Each of the revolving gear cases 8A, 8B, 8C supporting the wheels 4, 5, 6 is provided with a wheel 4,
By attaching potentiometers 10L, 10R, and 10D that can detect the steering angles of 5 and 6, respectively, the present steering angle can always be detected.

The forklift has a brake for traveling. In this embodiment, a brake operation detecting means 23 comprising various switches capable of detecting an operation state of a pedal 24 for operating the brake is provided. Are illustrated. The brake pedal 24 is
The spring is urged upward and the pedal 2
A so-called deadman type brake is used, which is released by depressing the pedal 4 and brakes by releasing the foot from the pedal 24.

In the present embodiment, the forklift 1
A mode selecting device 19 that can select one driving mode from among the plurality of driving modes, and a control unit C that can switch the driving mode to the selected driving mode in response to a mode signal from the mode selecting device 19. Have.

As shown in FIG. 1, for example, the mode selection device 19 is arranged near the driver's seat of a forklift, for example, in an instrument panel, and may be formed by a plurality of push button switches. In the present embodiment, the instrument panel in the driver's seat includes a display unit 21 formed of a liquid crystal display or the like. The display unit 21 is useful for displaying the current driving mode and giving other appropriate information to the driver.

As shown in FIG. 2, the control unit C includes a CPU as a central processing unit, a ROM as storage means for storing processing procedures of the CPU and known data in advance, and a temporary storage memory for work. And the input port I
An example is shown that includes a P, an output port OP, and a data bus connecting these appropriately.

A forklift traveling speed signal V output from the speed sensor 22 is input to the input port IP.
A brake operation signal Bk output from the brake operation detection means 23, a travel instruction signal Ac output from the accelerator device 20, and the potentiometers 10D, 10D,
The steering angle signals θD, θL, and θR of the respective wheels output from 0L and 10R are input.

The CPU performs predetermined processing based on these input signals, and at the same time, through the output port OP, the forklift traveling controller 30 and the display unit 2.
1. Servo controller 32 for left and right road wheels
Various signals that can control these are output to L and 32R.

Next, the traveling mode of the forklift will be described. In this example, as shown in FIG. 3A, the rotation axes of the left and right road wheels 4 and 5 are fixed so as not to be steerable at positions along the vehicle body width direction, and the drive wheel 6 is steered. The vehicle is configured to be able to travel in a plurality of traveling modes including a normal traveling mode in which the direction of the vehicle body can be changed, and at least one or more special traveling modes other than the normal traveling mode.

As the special driving mode, for example, FIG.
As shown in (b), the steering angle θD of the left and right road wheels 4 and 5 is added to the steering angle θD of the drive wheel 6.
By controlling the L and θR to be equal to each other, a parallel traveling mode in which the vehicle body can be moved without changing the direction of the vehicle body, or turning the vehicle body with a substantially minimum turning radius as shown in FIG. A turning traveling mode to be performed can be included.

In the present invention, the control unit C permits switching of the mode when the traveling speed of the forklift 1 is 0 and the brake is in a stopped braking state. And

Thus, when the forklift travel mode is switched, the mode is not stopped during traveling because the forklift is always stopped and the brake is applied, and the traveling mode can be switched on a slope. In this case, it is possible to reliably prevent the forklift from running due to inertia, thereby improving the safety at the time of mode switching.

The mode switching will be specifically described. For example, when the traveling mode is switched from the normal traveling mode in FIG. 3A to the omnidirectional traveling mode in FIG. 3B, the forklift is stopped and By applying the brake and selecting the omnidirectional driving mode by the mode selecting means, the left and right road wheels 4,
5 is the steering angle θ of the drive wheel.
The steering is performed so as to coincide with D.

In this embodiment, the control unit C determines that the traveling speed of the forklift 1 is 0 and the brake 24
The mode switching process is performed by permitting the switching of the traveling mode during the stop braking state in which the forklift is acting, but when the mode switching is completed, for example, the accelerator device 20 is operated and the traveling instruction of the forklift is given. FIG. 1 illustrates an example in which the traveling of the forklift is prohibited until the traveling instruction is temporarily stopped.

This is because when the traveling mode is switched, the traveling pattern is often different from the previous traveling mode, and therefore, for example, the traveling mode is set to effectively prevent the forklift from starting in an unexpected direction. Unless the accelerator operation or the like that has been continued before the switching is once canceled, the driving in the new driving mode that has been switched is forbidden.

In the present embodiment, the control unit C
The display unit 2 indicates that the driving mode switching process is being performed.
1 is displayed. by this,
This is preferable in that the driver can easily recognize that the driving mode is currently being switched.

An example of such control will be described with reference to a flow chart shown in FIG. 4, taking as an example a case where the traveling mode exists from 1 to n (n is an integer of 2 or more).
When the key switch of the forklift is turned on, first, the on / off port I / O, RAM, running mode, etc. are initialized (step S1), and an initial (initialization) check of the running mode is performed (step S2).

When the running mode is initialized (Y in step S2), an operation start check of each hardware is performed (step S3). If the operation can be started normally (OK in step S3), this operation is started. In the example, first, driving mode 1
Are set (step S4).

Next, when the initialization of the driving mode is completed, the process returns to step S2 and proceeds to step S5. Step S
In 5, it is determined whether or not the current running mode is “running mode 1”. In the case of the traveling mode 1 (Y in step S5), it is determined whether or not the switching to the traveling mode 1 has already been completed (step S6). If the switching to the traveling mode 1 has not been completed yet ("not yet" in step S6), a traveling mode 1 switching process defined in another routine is performed (step S8).

In the traveling mode 1 switching process, first, as shown in FIG. 5, the controller C outputs a traveling prohibition signal for prohibiting traveling to the traveling controller 30 (step S81). Then, a traveling mode switching signal for displaying that the traveling mode is currently being switched is output (step S82). Then, the steering angles θL and θR of the left and right road wheels 4 and 5 are controlled to predetermined steering angles according to the traveling mode selected by the traveling controller.

Next, it is determined whether or not the switching of the traveling mode has been completed (step S83). If it has not been completed ("not" in step S83), the traveling mode switching process is terminated. If the switching of the traveling mode has been completed, it is determined whether or not there is a traveling instruction from the accelerator device 20 (step S84).

Here, when there is a traveling instruction from the accelerator device 20 ("Yes" in step S84), the traveling mode switching processing is terminated without setting the traveling mode switching completion signal. On the other hand, when there is no traveling instruction from the accelerator device 20 ("No" in step S84), the traveling mode switching completion signal is set, and the traveling mode switching process ends (step S85). As described above, even when the switching of the driving mode is substantially completed, the accelerator device 20
When there is a traveling instruction from the controller, the traveling mode switching completion signal is not set.

If the switching to the traveling mode 1 has already been completed ("Completion" in step S6), traveling in the traveling mode 1 is performed according to a predetermined rule (step S7).

Next, the control unit C checks whether or not the brake is operating from the brake operation detection signal BK (step S9). If the brake is not operating, the process returns to step S1. When the brake is operating (step S10), it is checked from the traveling speed signal V whether the current traveling speed is 0 km / H (step S1).
0), if it is not 0 km / H (N in step S10), the process similarly returns to step S1.

As described above, when the brake is not actuated or when the traveling speed is not 0, the processing for accepting the traveling mode switching signal from the traveling mode selecting means 19 (step S11) is skipped. Thus, switching to another driving mode can be prohibited. On the other hand,
When the brake is operated (Y in step S9) and the traveling speed of the forklift is 0 km / h (step S9)
At 10 (Y), the mode switching is permitted by inputting the mode signal md from the driving mode selecting means 19 (step S11). The switching check of the traveling mode is performed up to the traveling mode n in the same procedure.

Although described in detail above, the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made to the processing procedure of the CPU so as to achieve the same function. In addition, the special driving mode employs various driving modes other than the example driving modes, such as a traversing driving mode in which the vehicle can steer while traveling sideways, and a reverse phase mode in which the drive wheel and the road wheel are steered in opposite directions. sell.

[0040]

As described above, according to the first aspect of the present invention, when the forklift travel mode is switched, the forklift is always stopped, and the brake is applied. Switching can be prevented, and the forklift can be reliably prevented from running by inertia during switching of the traveling mode on a slope or the like, and safety at the time of mode switching can be improved.

According to the second aspect of the present invention, the control unit performs the mode switching process by permitting the switching of the traveling mode, and if the forklift traveling instruction is issued when the mode switching is completed, the controller issues the traveling instruction. By prohibiting the forklift from running until it is temporarily stopped, the forklift can immediately start immediately after mode switching, or can cancel the driving instruction that was operated assuming the previous driving mode, thus providing more safety when switching modes. Sex can be further enhanced.

According to the third aspect of the present invention, the control section displays on the display section that the driving mode switching process is being performed, so that the driver can easily be informed that the mode switching is being performed. Yes, it is possible to self-restrain driving instructions.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a reach type forklift showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a control device.

FIGS. 3 (a) to 3 (c) are diagrams illustrating driving modes.

FIG. 4 is a flowchart illustrating a control procedure according to the embodiment.

FIG. 5 is a flowchart illustrating a control procedure according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Forklift 19 Running mode selection means 20 Accelerator device 21 Display part 22 Speed sensor 23 Brake operation detection means C Control part

Claims (5)

[Claims] 1. A forklift capable of traveling in a traveling mode selected from a plurality of traveling modes, comprising: a mode selecting means capable of selecting the traveling mode; and a traveling mode selected by a mode signal from the mode selecting means. A control unit capable of switching to the selected traveling mode, wherein the control unit permits the switching of the mode when the traveling speed of the forklift is 0 and the brake is in a stop braking state. A forklift characterized by the following. 2. The control section performs a mode switching process by permitting the switching of the traveling mode, and, when a traveling instruction of a forklift is issued when the mode switching is completed, the controller continues until the traveling instruction is temporarily stopped. The forklift according to claim 1, wherein traveling of the forklift is prohibited. 3. The forklift according to claim 1, wherein the control unit causes the display unit to display that the driving mode is being switched. 4. A forklift, comprising: a load wheel steerably supported by left and right straddle arms;
A drive wheel that can be steered and rotated by a steering wheel, and a steering angle detecting means for detecting a steering angle of the drive wheel, wherein the rotation axis of the road wheel is steered at a position along a vehicle width direction. A plurality of traveling modes including a normal traveling mode fixed to impossible and capable of changing the direction of the vehicle body by steering the drive wheel, and at least one or more special traveling modes other than the normal traveling mode The forklift according to any one of claims 1 to 3, wherein the forklift is formed so as to be able to travel. 5. The special traveling mode includes a parallel traveling mode in which the steering angle of the drive wheel and the steering angle of the left and right road wheels are substantially matched to allow the vehicle to move without changing the direction of the vehicle body. 5. A forklift according to claim 4, further comprising: a turning traveling mode in which the turning is performed with a substantially minimum turning radius.