JP3306353B2 - Reach type forklift - Google Patents

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 capable of improving maneuverability in lateral movement.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
Drive hole e that can be steered by the steering wheel
And road wheels c and d slidably attached to left and right straddle arms f and f projecting from the vehicle body a, and control means for controlling a steering angle of the road wheels c and d. The reach type forklift capable of traveling in the direction is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 5-116664,
JP-A-5-178232, JP-A-5-20134
9, JP-A-5-221334, JP-A-5-221334
246699 and the like.

Further, as shown in FIG. 12, such a reach type forklift can perform a lateral movement of changing the direction of the vehicle body while traveling in a right or left lateral direction orthogonal to the vehicle body center line CL. By such lateral movement, there is an advantage that the vehicle can laterally move into the narrow passage b and enter the narrow passage b, and can carry cargos or the like arranged facing the passage.

[0004]

The above-mentioned lateral movement is performed by steering one of the left and right road wheels c and d in advance, for example, the right road wheel d in parallel with the lateral direction, and by using the steering wheel. By steering the drive wheel e, a turning center point P at which the right road wheel d intersects with the extension line of each rotation axis of the drive wheel e is calculated, and the turning center point is set to the left road wheel c. The vehicle is turned in the lateral direction by steering so that the extension lines of the rotating shafts intersect.

However, in such a lateral movement, when one of the road wheels c and d, in this example, the right road wheel d is steered in parallel in the lateral direction, if the lateral movement direction is right, the vehicle turns. The axis where the center points are aligned is the leading side in the traveling direction, but when the lateral movement direction is left, the axis where the turning center points are aligned is the rear side in the traveling direction, and the driving feeling differs in the direction of the lateral movement, There was a problem of poor maneuverability.

The present invention has been devised in view of the above-described problems, and has a reach-type forklift capable of improving the operability of lateral movement by making the driving feeling the same regardless of the direction of lateral movement. It is intended to provide.

[0007]

According to a first aspect of the present invention, a drive hole provided in a vehicle body and rotatably driven by a prime mover, and left and right straddle arms protruding from the vehicle body are provided. A steering wheel mounted on the straddle arm, and control means for controlling a steering angle of the steering wheel. A reach-type forklift capable of performing a lateral movement changing the right virtual steering wheel and the left virtual steering wheel set side by side in the lateral direction on the rear side in the moving direction of the lateral movement. A lateral direction setting process for virtually steering the one virtual steered wheel in parallel with the lateral direction, and temporarily setting the other virtual steered wheel based on a steering angle command value corresponding to a steering operation. And a virtual steering process of steering, right,
A virtual turning center point calculation process for calculating a virtual turning center point at which the extension line of the rotation axis of the left virtual steering wheel intersects, and an extension of each of the rotation axes of the left and right road wheels and the drive wheel to the virtual turning center point. A target steering angle calculation process for calculating each target steering angle at which a line intersects, and a steering angle control process for controlling the left and right road wheels and drive wheels to the target steering angles are performed.

According to 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 operation of the steering wheel. The reach-type forklift according to claim 1, further comprising a steering wheel sensor, wherein the drive wheel is steered by steering means including an electric motor.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 mast device M that moves back and forth along the straddle arms 3L and 3R and has a fork F as a cargo handling tool in this example. I have.

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 embodiment, the handle H has a non-coupling state mechanically separated from the drive wheel 6, as shown in FIG. 3, and steers the drive wheel 6 by a so-called fly-by-wire method. are doing. That is, the steering wheel H has a steering wheel sensor 16 that outputs a steering angle command value θS 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. By doing so, the drive wheel 6 can be steered. In this example, the steering center point of the drive wheel 6 is point 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
Is driven by a drive signal from a control device 17 described later. This drive signal can be determined based on the steering angle command value θS based on the operation of the steering wheel H.

As the handle sensor 16, for example, a potentiometer or an encoder capable of detecting the rotation angle of the handle H can be used, and a change in the rotation angle of the handle H within a unit time is detected. Can be included as the command information. In the case where the handle H and the drive wheel 6 are in a mechanically uncoupled state as in this example, a stopper or the like for limiting the rotation angle of the handle H to a predetermined range is provided mechanically or electrically. It is desirable.

Each of the swing gear cases 8A, 8B, 8
The potentiometers 10L, 10R, and 10D that can detect the steering angles of the wheels 4, 5, and 6, respectively, are attached to C, so that the current steering angle can always be detected.

FIG. 2 illustrates a control device 17 for such a reach type forklift. In the figure, a control device 17 includes a CPU as a central processing unit, a ROM as a storage unit in which a processing procedure of the CPU, known data, and the like are stored in advance, a RAM as a temporary storage memory for work,
An input / output port I / O, a data bus connecting these as appropriate, a motor controller 20 for driving and controlling the servo motors 9L, 9R attached to the left and right road wheels 4, 5 and the servo motor 9D for steering the drive wheel 6;
L, 20R, and 20D are illustrated.

The input I / O ports include steering angles θD of the potentiometers 10D, 10L, and 10R, respectively.
θL, θR, a steering angle command value θH of the handle sensor 16 and the like are input. In the present embodiment, the CPU calculates the target steering angles θLO, θRO, θDO, etc. of the left and right road wheels 4, 5 and the drive wheel 6 by using the respective signals in accordance with the processing procedure stored in the ROM, The target steering angle and the like are output to the motor controllers 20L, 20R, 20D via the output port I / O.

The reach type forklift 1 of this embodiment can switch between two or more driving modes. In this example, as shown in FIG.
The steering angles θL and θR of the drive wheel 6
11B, the left and right road wheels 4 and 5 are steered and fixed in a straight-ahead state, and a drive wheel is provided. Normal mode in which the body direction is changed by steering only 6
As shown in (c), the vehicle can travel in a plurality of traveling modes such as an in-situ turning mode in which the left and right road wheels 4 and 5 have a substantially C-shape and an angle capable of turning with a minimum turning radius. Each of these traveling modes is exemplified by a mode in which the traveling can be appropriately switched by a changeover switch 19 (shown in FIG. 1) disposed near the driver's seat or the like.

Then, the reach type forklift 1 of this embodiment
In addition to the above-mentioned traveling modes, as shown in FIGS. 4 to 6, a lateral movement that changes the direction of the vehicle body while traveling in the right or left lateral direction orthogonal to the vehicle body center line CL (hereinafter, simply referred to as a lateral movement mode). ), And the lateral movement mode of the present embodiment is characterized in that the driving feeling can be the same regardless of the direction of the rightward or leftward lateral movement.
Hereinafter, the processing procedure will be described with an example in which the direction of the lateral movement is the left as shown in FIG.

First, as shown in FIG. 4, the control device 17 controls one of the right virtual steering wheel VR and the left virtual steering wheel VL, which are set side by side, on the rear side in the moving direction of the lateral movement. Virtual steering wheel, that is, the right virtual steering wheel VR
Is performed in the horizontal direction to steer the wheel in parallel with the horizontal direction.
In this example, the left and right virtual steering theories VL and VR are illustrated as being provided at symmetrical positions with respect to the vehicle body center line CL. As shown in FIG. 4, the direction of the lateral movement is defined as left and right with the vehicle body facing forward.

A "virtual steering wheel" is a non-existent steering wheel provided for determining a turning center point P of a reach-type forklift when given a steering command value, and is fixed on the reach-type forklift. The virtual plane coordinates XY are provided.

In this embodiment, the plane coordinates XY are:
As shown in FIG. 4, an X-axis passing through the steering center point R of the right road wheel 5 of the reach type forklift 1 and parallel to the vehicle body center line CL, the steering center point L or R of the left or right road wheel 4 or 5, and , And a Y-axis passing through an intermediate position between the steering center point D of the drive wheel 6. In this example, the steering center point VRC of the right virtual steering wheel VR is provided on the origin of the coordinates, and the steering center point VLC of the left virtual steering wheel VL is set on the Y axis and the left road wheel. The example provided at the position of the same Y coordinate value as the steering center point L is illustrated. The positions of the virtual steered wheels are not limited to this example, and may be provided at various positions as shown by the dotted lines in FIG.

Next, the controller 17 virtually steers the other virtual steered wheel, in this example, the left virtual steered wheel VL, based on the steering angle command value θS corresponding to the operation amount of the steering wheel H.

Next, virtual turning center point calculation processing for calculating a virtual turning center point P at which the extended lines VR1, VL1 of the rotation axes of the left and right virtual steered wheels VL, VR intersect is performed. The X coordinate value Xp of the turning center point P (Xp, 0) is obtained by the following equation, where B is a virtual wheel base that is the Y direction distance between the steering center points VLC and VRC of the left and right virtual steered wheels. Can be. Xp = B / tan (θS) ...

Next, extension lines L1, R1, D1 of the respective rotation axes of the left and right road wheels 4, 5 and the drive wheel 6 are located at the virtual turning center point P obtained by the above calculation.
Is performed, the target steering angle calculation processing is performed to calculate the target steering angles θLO, θRO, and θDO where. Each target steering angle θLO, θ
RO and θDO are obtained by the following formulas, where A is the actual wheelbase that is the X-direction distance between the steering center point L or R of the left and right road wheels 4 and 5 and the steering center point D of the drive wheel. be able to. θLO = tan ^-1 {B / (Xp-0.5A)} ... θRO = 0 ... θDO = tan ^-1 {B / (Xp + 0.5A)} ...

Next, the left and right road wheels 4, 5 and the drive wheel 6 are moved to the target steering angles θLO, θR.
A steering control process for steering to O and θDO is performed. In this processing, the target steering angles θLO, θLO,
θRO and θDO correspond to the motor controllers 20L and 20L.
R, 20D and the motor controller 20
L, 20R, and 20D can drive the servo motors 9L, 9R, and 9D such that the deviation between the current steering angles θL, θR, and θD and the target steering angles θLO, θRO, and θDO becomes zero.

When the lateral movement direction is right, as shown in FIG. 6, the left virtual steering wheel VL is steered in parallel with the lateral direction, and then a steering angle command according to the operation amount of the steering wheel H is issued. Value θ
Based on S, the right virtual steered wheel VR is virtually steered by θS.

Next, a virtual turning center point calculation process for calculating a virtual turning center point P at which the extension lines VR1, VL1 of the rotation axes of the left and right virtual steered wheels VL, VR intersect is performed. The turning center point P (Xp, B) can be obtained by the following equation, where B is the distance in the Y direction between the steering center points VLC and VRC of the left and right virtual steered wheels. Xp = B / tan (θS) ...

Next, extension lines L1, R1, D1 of the respective rotation axes of the left and right road wheels 4, 5 and the drive wheel 6 are located at the virtual turning center point P obtained by the above calculation.
Is performed, the target steering angle calculation processing is performed to calculate the target steering angles θLO, θRO, and θDO where. Each target steering angle θLO, θ
RO and θDO are obtained by the following equations (1) and (2), and the steering angle control processing is performed. θLO = 0 ... θRO = tan ^-1 {B / (Xp-0.5A)} ... θDO = tan ^-1 {B / (Xp + 0.5A)} ...

As described above, according to the present invention, the right or left virtual steering wheel VR, VL on the rear side in the traveling direction of the lateral movement is steered in parallel with the lateral direction, and the other virtual steering wheel is steered by the steering amount of the steering wheel H. , The turning center point is located in the rear of the traveling direction regardless of the traveling direction of the lateral movement, so the driving feeling when changing the direction of the vehicle body is the same, and the steering of the lateral movement is The properties can be greatly improved.

Further, the reach type forklift 1 traverses while satisfying the so-called Ackerman-Jantt theory in which the extension line of the rotation axis of the drive wheel 6 and the left and right road wheels 4 and 5 crosses one rotation center point P and turns. Therefore, there is an advantage that the slip of each wheel is minimized and a smooth lateral movement operation can be realized.

Further, once the operation amount of the steering wheel H is given to the virtual steered wheels VR or VL, the virtual wheel base B between the steering center points VRC and VLC of the right and left virtual steered wheels VR and VL is variously set. Or by setting the actual wheelbase A to be equal to the actual wheelbase A, for example, to realize the driving feeling in the lateral movement based on the same wheelbase as in the normal traveling in which the reach type forklift 1 travels in the direction of the vehicle center line CL. Can also.

Further, since one virtual steering wheel on the rear side in the traveling direction of the lateral movement is virtually steered in parallel with the lateral direction, the turning center point P is continuously arranged on the rear side in the traveling direction of the lateral movement. As a result, the steering can be performed with a so-called driving feeling of a car, and the maneuverability can be further improved.

In the case of such a lateral movement, in a case where the direction of the lateral movement in the right direction is switched to the left direction, it is preferable that there is no break in control. FIGS. 7 and 8 show detailed processing procedures performed by the CPU for preventing such control breaks.

In the figure, the CPU has an input port I / O
Then, the steering angle command value θS corresponding to the steering operation is read from the controller (step S1), and thereafter, the traveling direction of the lateral movement is checked (step S2). The traveling direction can be detected from the tilt direction of the accelerator device AC.

Next, if the lateral movement direction is left (Y in step S2), the steering angle θVR of the right virtual steering theory VR approaches the angle α at which the steering angle θVR approaches 0, regardless of which direction the steering wheel is operated. Ask. As shown in FIG. 7, this angle α is processed in four types based on a combination of the sign of the steering angle command value θS and the steering θVR of the right virtual steered wheel VR (steps S5 to S7, S8). -10, S11-14, S15-
17). Each angle is positive in the counterclockwise direction and is 0 degrees in the state shown in FIG.

Next, the steering angle θVR of the right virtual steering wheel VR
Angle β between the angle α and the angle α is determined (step S1).
8). Further, the steering angle θVR of the right virtual steered wheel VR is set to an angle α (step S19). As a result, the steering angle θVR of the right virtual steered wheel VR approaches 0 to 0 degrees. Further, the steering angle θVL of the left virtual steered wheel VL can be obtained by subtracting the angle β from the steering angle command value θS (step 20).

On the other hand, when the lateral movement direction is right (N in step S2), as shown in FIG. 8, the steering angle θ of the left virtual steered wheel VL is obtained regardless of which direction the steering wheel H is operated.
The angle α at which VL approaches 0 is determined. This angle α is shown in FIG.
, The steering angle command value θS and the left virtual steering wheel V
Depending on the combination of the sign of L with the steering angle θVL, processing is performed in four types (steps S26 to S28, S32 to S32
4, S35-38, S39-41).

Next, the steering angle θVL of the left virtual steering wheel VL
Angle β between the angle α and the angle α is determined (step S2).
9). The steering angle θVL of the left virtual steered wheel VL is determined as the angle α (step S30). As a result, the steering angle θVL of the left virtual steered wheel VL approaches 0 to 0 degrees. The steering angle θVR of the right virtual steered wheel VR is obtained by subtracting the angle β from the steering angle command value θS of the steering wheel (step S31).

Based on the steering angles θVL and θVR of the left and right virtual steered wheels VL and VR obtained as described above, the above-described virtual turning center point calculation processing, target steering angle calculation processing, and steering angle control processing are performed. The forklift can move sideways.

Thus, the right and left virtual steered wheels V
By determining the steering angles θVR and θVL of R and VL, even when the direction of the lateral movement is changed, the Ackerman-Jantt theory can be satisfied without having a control break as shown in FIG.

FIG. 10 shows another embodiment of the present invention. In the present embodiment, an example is shown in which clutch means 24 capable of mechanically engaging and disengaging the handle H and the drive wheel 6 is provided. An input shaft 27 to which rotation of the handle H is transmitted via a chain 25 is connected to an input side 24i of the clutch means 24. 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. In addition, the motor 9D for steering at the time of fly-by-wire is attached to the speed reducer G as in the above embodiment.

In the lateral movement 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 angle command value DS corresponding to the amount can be used as an output value to the virtual steered wheels VL and VR without steering the drive wheel 6. On the other hand, when it is necessary to steer the drive wheel 6 such as in a normal mode, the steering wheel H and the drive wheel 6 may be mechanically linked by engaging the clutch means 24.

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, Has the advantage that existing forklifts can realize the lateral movement mode with few modifications,
The present invention can be modified in various modes.

[0045]

As described above, according to the first aspect of the present invention, the virtual steering wheel on the rear side in the traveling direction of the lateral movement is steered parallel to the lateral direction, and the other virtual steering wheel is adjusted to the steering amount of the steering wheel. In response to virtual steering, regardless of the traveling direction of the lateral movement, the turning center point is always located in the rearward direction in the traveling direction, so the driving feeling when changing the body direction becomes the same,
The maneuverability of the lateral movement can be greatly improved. In addition, the reach-type forklift can move laterally while satisfying the so-called Ackerman-Jantt theory in which the extension of the rotation axis of the drive wheel and the left and right road wheels crosses at one turning center point, so that each wheel slips. There is an advantage that it can be minimized and a smooth lateral movement operation can be realized.

Also, once the steering amount is given to the virtual steered wheels, the distance between the steering centers of the right and left virtual steered wheels is set, and various gains are given to the steering amount. Thereby, for example, the same driving feeling as in normal traveling in which the reach type forklift travels in the vehicle center line direction can be realized in the lateral movement.

Further, since the one virtual steering wheel on the rear side of the lateral movement is virtually steered in parallel with the lateral direction, the turning center point is continuously arranged on the rear side in the moving direction of the lateral movement. As a result, the steering can be performed in a vehicle-like manner, and the maneuverability can be improved.

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 operation of the steering wheel. By providing the steering wheel sensor, it is possible to give command information to virtual steered wheels without steering the drive wheel. In addition, the drive wheel can be steered to the target steering angle by being steered by a steering unit including an electric motor even when the drive wheel is mechanically separated from the steering wheel.

[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 related state between a drive wheel and a steering wheel.

FIG. 4 is a plan view illustrating a lateral movement mode of the reach type forklift.

FIG. 5 is a plan view illustrating a lateral movement mode of the reach type forklift.

FIG. 6 is a plan view illustrating a lateral movement mode of the reach type forklift.

FIG. 7 is a flowchart illustrating a control procedure according to the embodiment.

FIG. 8 is a flowchart illustrating a control procedure according to the present embodiment.

FIG. 9 is a plan view illustrating a state at the time of switching the direction of the lateral movement.

FIG. 10 is a conceptual diagram showing another example of the linked state between the drive wheel and the handle.

FIGS. 11A to 11C are plan views for explaining a traveling mode of a reach type forklift.

FIG. 12 is a plan view for explaining lateral movement of a conventional reach-type forklift.

[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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 7/14 B62D 6/00 B66F 9/10 B66F 9/24

Claims (2)

(57) [Claims] A drive hole provided in 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; Control means for controlling the steering angle of the road wheel, a reach-type forklift capable of performing a lateral movement changing the direction of the vehicle body while traveling in a right or left lateral direction orthogonal to the vehicle body center line, wherein the control The means virtually steers the one virtual steering wheel, which is the rear side of the lateral movement in the right virtual steering wheel and the left virtual steering wheel set side by side in the lateral direction, in parallel with the lateral direction. A lateral direction setting process, a virtual steering process for virtually steering the other virtual steered wheel based on a steering angle command value corresponding to a steering operation, and a rotation of the right and left virtual steered wheels. A virtual turning center point calculation process for calculating a virtual turning center point at which the extension line of the axis intersects; and each target steering angle at which the extension line of the rotation axis of each of the left and right road wheels and the drive wheel intersects this virtual turning center point. And a steering angle control process of controlling the left and right road wheels and drive wheels to the target steering angle. 2. The steering wheel according to claim 1, wherein the steering wheel has a non-coupling state mechanically separated from the drive wheel, and further includes a steering wheel sensor for outputting a steering command value for outputting a signal corresponding to the operation of the steering wheel. The reach-type forklift according to claim 1, wherein the drive wheel is steered by steering means including an electric motor.