JPH11105731A - Reach type fork-lift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reach type fork-lift truck which can be maneuvered with the feeling of an automobile. SOLUTION: This fork-lift truck is provided with a drive wheel 6 fitted on a vehicle body part 2, right and left load wheels 4, 5 mounted on straddle arms so as to be maneuvered, and a control means for controlling the steering angle of the road wheels 4, 5, whereas the drive wheel 6 is fixed in the advancing direction parallel to the center line of a vehicle body, and the right and left load wheels 4, 5 are steered based on the operation of a steering wheel H, thus it is possible to change the direction of the vehicle body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reach-type forklift that can be operated like an automobile.

[0002]

2. Description of the Related Art A conventional reach type forklift is shown in FIG.
As shown in FIG. 1, a drive wheel e provided on the vehicle body main body a and rotatable by, for example, an electric motor, and left and right straddle arms b projecting from the vehicle body main body a,
b, road wheels c, c which are non-steerably mounted. The drive wheel e has a handle h
The steering is made freely by the operation of.

In such a reach type forklift, when the handle h is operated, the drive wheel e can be steered, and an extension line e1 of the rotation axis of the drive wheel e is provided.
And an extension line c1 of the rotation axis of the left and right road wheels c, c.
Is the turning center point d, and the direction of the vehicle body can be changed around the turning center point d.

[0004]

As shown in FIG. 9, a front wheel i is steered by operating a steering wheel and an extension line j of a rotation axis of a rear wheel j is provided.
The turning of the vehicle body is performed at a turning center point P, which is a point where the upper line 1 and the extension lines i1 and i2 of the rotation axis of the front wheel i intersect. For this reason, a reach-type forklift in which the turning center point d is arranged on the rotation axis c1 of the road wheel c (front wheel) is completely different from the driving feeling of an automobile, and it is difficult to operate the forklift such as turning the vehicle body. In addition to requiring skills,
In particular, those who are accustomed to driving a car have the problem that it takes a lot of time to acquire the driving feeling of the reach type forklift.

The present invention has been devised in view of the above problems, and has as its object to provide a reach-type forklift that can be operated like a car.

[0006]

According to a first aspect of the present invention, a drive wheel provided on a vehicle body and rotatably driven by a prime mover, and left and right straddle arms protruding from the vehicle body are provided. A road wheel that is steerably attached to the straddle arm,
A reach-type forklift comprising control means for controlling a steering angle of the road wheel, wherein the drive wheel is fixed in a rectilinear direction parallel to a vehicle body center line, and the left and right loads are controlled based on an operation of a steering wheel. It is characterized in that the direction of the vehicle body is changed by steering the wheel.

According to a second aspect of the present invention, there is provided a steering wheel sensor, wherein the steering wheel has a non-coupling state mechanically separated from the drive wheel and outputs a steering command value corresponding to the operation of the steering wheel. 2. The reach type forklift according to claim 1, wherein the control means steers the left and right road wheels based on the steering command value.

According to a third aspect of the present invention, the control means sets a virtual steering wheel preset at an arbitrary position on virtual plane coordinates fixed on a reach-type forklift based on an operation of the steering wheel. Virtual steering processing for steering,
A turning center point calculation process for calculating a turning center point where an extension of the rotation axis of the steered virtual steered wheel intersects with an extension of the rotation axis of the drive wheel; 2. A process for calculating a target steering angle of the left and right road wheels at which the extension line of the rotation axis intersects, and a road wheel steering process for steering the left and right road wheels to the target steering angle.
Or a reach-type forklift according to 2.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a reach type forklift 1 of the present embodiment is a steerable left and right road wheel attached to a left and right straddle arm 3 </ b> L, 3 </ b> R projecting forward from a vehicle body 2 so as to control a steering angle. 4, 5; a drive wheel 6 provided on the vehicle body 2; and a fork F that moves back and forth along the straddle arms 3L and 3R, and in this example serves as a cargo handling device.
And a mast device M having the following.

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 steering center point of each of the road wheels 4, 5 is set at the center position L, R in the width direction and the circumferential direction of the wheel.

The drive wheel 6 is an electric motor M (shown in FIG. 3) as a prime mover driven by a battery.
It is linked with. The rotational driving force of the drive wheel 6 can be adjusted by operating an accelerator device AC provided in a driver's seat.

In this embodiment, the drive wheel 6 can be steered by operating the steering wheel H. In the present example, the handle H has a non-coupling state mechanically separated from the drive wheel 6 as shown in FIG. 3, and is used to steer the drive wheel 6 by a so-called fly-by-wire system. An example is shown. That is, the steering wheel H has a steering wheel sensor 16 that outputs a steering command value corresponding to the operation of the steering wheel H, and rotationally drives a servo motor 9D that steers the drive wheel 6 according to the output of the steering wheel sensor 16. Thus, the drive wheel 6 can be steered. In the present example, the drive center of the drive wheel 6 is illustrated as D as shown in FIG.

As shown in FIG. 3, in the present embodiment, the drive wheel 6 is attached to the vehicle body 2 in a freely rotatable manner, and has a turning gear case 8A having an electric motor M for rotational driving directly connected to an upper portion thereof. It is pivoted. A servomotor 9D for steering is attached to the turning gear case 8A via a speed reducer G. Servo motor 9D
Are driven by a drive signal from the control device 17.
This drive signal can be determined based on a steering command value based on the operation of the steering wheel.

The handle sensor 16 can be, for example, a potentiometer capable of detecting the rotation angle of the handle H, and detects a change in the rotation angle of the handle H within a unit time to determine the angular velocity of the handle H. ω can also be included in the steering command value. When the steering wheel H and the drive wheel 6 have a mechanically uncoupled state as in this example, a stopper for limiting the rotation angle of the steering wheel H or the drive wheel 6 to a predetermined range is mechanically or electrically operated. It is desirable to be attached in a special way.

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.

Next, FIG. 2 shows an example of such a reach type forklift control device 17. In the figure, a control device 17 includes a CPU as a central processing unit, a CP,
A ROM as a storage means in which the processing procedure of U and known data are stored in advance, and an R as a temporary storage memory for work
AM, input and output ports I / O, data buses for connecting these appropriately, and motors for driving and controlling servo motors 9L and 9R attached to the left and right road wheels 4 and 5 and a servo motor 9D for steering the drive wheel 6 An example is shown that includes controllers 20L, 20R, and 20D.

The input I / O ports include steering angles θD of the potentiometers 10D, 10L, and 10R, respectively.
The signals θL and θR, the steering command value θH of the steering wheel sensor 16, and the switching signal md from the mode switching device 19 in this example are input (the mode switching device 19 will be described later). In the CPU, each of the signals is RO
In this example, the target steering angles θLO, θRO, θDO, etc. of the left and right road wheels 4, 5 and the drive wheel 6 are calculated by using the processing procedure stored in M, and the target steering angles and the like are output to an output port. It is configured to output to the motor controllers 20L, 20R, 20D via I / O.

Further, the reach type forklift 1 of the present embodiment can select and switch one of two or more driving modes by a mode switching device 19 disposed near the driver's seat. In this example, as shown in FIG. 7A, the steering angles θL and θR of the left and right road wheels 4 and 5 are
The parallel traveling mode in which the vehicle body moves obliquely vertically and horizontally while keeping the orientation of the vehicle body constant by matching with the steering angle θD of FIG.
(B) a normal mode in which the left and right road wheels 4 and 5 are steered and fixed in a straight traveling state, and only the drive wheel 6 is steered to change the direction of the vehicle body;
Further, as shown in FIG. 7C, the vehicle can travel in a plurality of types of traveling modes such as an in-situ turning mode in which each wheel can be turned with a minimum turning radius.

Then, the reach type forklift 1 of this embodiment
In addition to the above-mentioned driving modes, the drive wheel 6 is fixed in a straight traveling direction parallel to the vehicle body center line CL, and the left and right road wheels 4 5 is steered to change the direction of the vehicle body (hereinafter, may be simply referred to as “vehicle driving mode”).

Accordingly, the reach type forklift 1
The forward and backward running of the vehicle can be changed with the same feeling as the car, so if you are familiar with driving a car, the driving operability is greatly improved, and Can learn driving skills.

An example of such a control method of the reach type forklift 1 will be described with reference to a flowchart shown in FIG. First, when the vehicle driving mode is selected, the CPU drives the servo motor 9D to output the drive wheel to the motor controller 20D with the target steering angle θDO of the drive wheel set to 0 in the straight direction parallel to the vehicle body center line, that is, 0. The steering is fixed (step S1).

Next, the CPU reads the steering command value .theta.H from the handle sensor 16 into the RAM (step S2), and arbitrarily sets the virtual plane coordinates XY fixed on the reach-type forklift as shown in FIG. A virtual steering process is performed to steer a virtual steered wheel V set in advance at a position based on the operation of the handle H (step S3).
In the present embodiment, the virtual steering wheel V is steered by the steering command value θH of the steering wheel sensor 16. At this time, it goes without saying that various gains may be given to the output of the handle sensor 16.

As described above, in the present embodiment, since the steering wheel H is in a mechanically uncoupled state with the drive wheel 6, in the vehicle running mode, the steering command value θH of the steering wheel H is indicated by a virtual line. The steering theory V is used as information for steering the left and right road wheels 4 and 5 described later. On the other hand, the steering command value θ of the steering wheel H
Since H can be used as information for steering the drive wheel 6 in the normal mode, for example, a steering command is given to the drive wheel 6 or the left and right road wheels 4 and 5 with one handle H. This is preferable in that the steering command means can be shared.

In this embodiment, the plane coordinates XY are:
Y passing through the vehicle center line CL of the reach type forklift 1
And a virtual straight line connecting the virtual steering wheel V on the Y axis and connecting the steering center points L and R of the left and right road wheels 4 and 5 with the X axis passing through the steering center point D of the drive wheel 6. An example in which a steering center point C is provided on N is illustrated.

Here, the virtual steering wheel V is a steering wheel set to virtually determine the turning center point P of the reach type forklift by giving the steering command value θH of the steering wheel H. And can be provided at an arbitrary position of virtual plane coordinates XY fixed on the reach type forklift. When the steering center point C of the virtual steering wheel V is provided on the vehicle center line, the steering feeling becomes the same in left and right turns with the same handle operation amount, and the steerability is further improved. Also, by setting various distances B from the origin 0 of the plane coordinates XY to the steering center point C of the virtual steered wheels, the so-called steering feeling can be sharpened or dulled.

Next, the control device 17 determines a turning center at which the extension line V1 of the rotation axis of the steered virtual steering wheel V and the extension line of the rotation axis of the drive wheel, that is, the X axis of the plane coordinates, intersect. A turning center point calculation process for calculating the point P is performed (step S4).

In the case of the present embodiment, the turning center point P is arranged on the X axis in the vehicle running mode.
The X coordinate value of the turning center point P (Xp, 0) may be calculated. Here, assuming that the X coordinate value Xp of the turning center point P is θH for the steering angle of the virtual steering wheel V and B is the distance in the Y direction from the steering center point C of the virtual steering wheel V to the origin, It can be obtained by the following equation according to the geometric relationship. Xp = B / tan ^-1 (θH) ...

Next, when the turning center point P is determined, the target steering of the left and right road wheels 4, 5 at which the extension lines L1, R1 of the rotation axes of the left and right road wheels 4, 5 intersect the turning center point P, respectively. A process of calculating the angles θLO and θRO is performed (step S5). The target steering angles θLO and θRO of these left and right road wheels 4 and 5 can be obtained from the following equation, where A is the distance between the steering center points L and R of the left and right road wheels 4 and 5 in the X direction. it can. The positions of the steering center points L and R of the left and right road wheels 4 and 5 are provided symmetrically with respect to the Y axis. θLO = tan ^-1 {B / (Xp-0.5A)} ... θRO = tan ^-1 {B / (Xp + 0.5A)} ...

Next, a road wheel steering process for steering the left and right road wheels 4 and 5 to the target steering angles θLO and θRO is performed (step S6). In this processing, the left and right road wheels 4, 5 determined by the above equation are used.
Are output to the motor controllers 20L and 20R, and the motor controllers 20L and 20R reduce the deviation between the current steering angles θL and θR and the target steering angles θLO and θRO to zero. Can drive the servo motors 9L and 9R.

By performing such a control procedure, the reach type forklift 1 has a so-called Ackerman in which an extension of the rotation axis of the drive wheel 6 and the left and right road wheels 4, 5 crosses one turning center point P to turn. Since the theory of the Junt can be satisfied, there is an advantage that the slip of each wheel is minimized and a smooth turning operation can be realized.

FIG. 6 shows another embodiment of the present invention. In this example, the handle H and the drive wheel 6
And a clutch means 24 capable of mechanically engaging and disengaging between the two. Input side 2 of the clutch means 24
An input shaft 27 to which rotation of the handle H is transmitted via a chain 25 is connected to 4i. The handle sensor 16 is linked to, for example, a chain 25. The output side 24o of the clutch means 24 is connected to the output shaft 29 of the speed reducer G via a universal joint U. Note that the servomotor 9D for steering during fly-by-wire steering is attached to the speed reducer G, as in the above-described embodiment.

In the vehicle running mode, the clutch H is disengaged to form a non-coupling state in which the handle H and the drive wheel 6 are mechanically disconnected. The steering command value DH corresponding to the amount can be used as an output value to the virtual steering wheel V without steering the drive wheel 6. On the other hand, when it is necessary to steer the drive wheel such as in a normal mode, the clutch means 24
And the handle H and the drive wheel 6 can be mechanically linked.

As described in detail above, the present invention is not limited to the above-described embodiment.
A first handle and a second handle are provided, and the drive wheel 6 is steered by the first handle, and the second handle can be used for a steering angle command to the virtual steered wheels V. In this case, The present invention can be modified in various modes, such as having an advantage that an existing forklift can realize an automobile traveling mode with a small modification.

[0034]

As described above, according to the first aspect of the present invention, in the reach type forklift, the drive wheel is fixed in the straight traveling direction parallel to the vehicle body center line, and the left and right road wheels are operated based on the operation of the steering wheel. By steering the vehicle to change the direction of the vehicle body, it is possible to change the direction of the vehicle body in forward traveling and reverse traveling of the reach type forklift with the same feeling as the direction of the vehicle. Therefore, anyone who can drive a car can easily operate a reach-type forklift, which has been considered difficult in the past, and can improve driving skills in a short period of time, dramatically improving maneuverability. Can be enhanced.

According to the second aspect of the present invention, the steering wheel has a non-coupling state mechanically separated from the drive wheel, and outputs a steering command value for outputting a signal corresponding to the amount of rotation of the steering wheel. By providing the steering wheel sensor, the steering wheel can be operated while the drive wheel is fixed in the straight traveling state. Therefore, the steering angle command value can be suitably used as a signal for steering the left and right road wheels.

According to the third aspect of the present invention, since the extension lines of the rotating shafts of the drive wheel and the left and right load wheels of the reach type forklift can cross the one turning center point and turn, the so-called Ackerman junction theory can be satisfied. Slip of each wheel can be minimized, and a smooth turning operation can be realized.

[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.

FIG. 3 is a conceptual diagram showing an example of a linked state between a drive wheel and a steering wheel.

FIG. 4 is a plan view illustrating a vehicle traveling mode of a reach type forklift.

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

FIG. 6 is a conceptual diagram showing another example of the linked state between the drive wheel and the handle.

FIGS. 7A to 7C are plan views for explaining a traveling mode of a reach-type forklift.

FIG. 8 is a plan view for explaining turning of a conventional reach-type forklift.

FIG. 9 is a plan view for explaining turning of the automobile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reach type forklift 2 Body part 3L, 3R Straddle leg 4, 5 Road wheel 6 Drive wheel 16 Handle sensor 17 Control device H Handle P Minimum turning center point

Claims (3)

[Claims] A drive wheel provided on a vehicle body and rotatably driven by a motor; a road wheel having left and right straddle arms protruding from the vehicle body and attached to the straddle arm so as to be steerable;
A reach-type forklift comprising control means for controlling a steering angle of the road wheel, wherein the drive wheel is fixed in a straight-line direction parallel to a vehicle body center line, and the left and right loads are controlled based on an operation of a steering wheel. A reach type forklift characterized by changing the direction of the vehicle body by steering the wheels. 2. The control device according to claim 1, wherein the handle has a non-coupling state mechanically separated from the drive wheel, and includes a handle sensor for outputting a steering command value corresponding to the operation of the handle. 2. The reach type forklift according to claim 1, wherein the left and right road wheels are steered based on the steering command value. 3. The virtual control system according to claim 1, wherein the control means is configured to perform a virtual steering process for steering a virtual steerable wheel preset at an arbitrary position on a virtual plane coordinate fixed on a reach-type forklift based on an operation of the steering wheel. A turning center point calculation process for calculating a turning center point at which an extension line of the rotation axis of the steered virtual steered wheel intersects with an extension line of the rotation axis of the drive wheel; 2. A process for calculating a target steering angle of the left and right road wheels at which the extension of the rotation axis intersects, and a road wheel steering process for steering the left and right road wheels to the target steering angle. Or the reach type forklift according to 2.