JP2001010522A - Steering controller for fork lift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering controller capable of providing the stable travelling without freely rotating tires even when a steering wheel is not operated in the steering controller having a handle and the steering wheel not mechanically connected to each other. SOLUTION: In this steering controller of a fork lift truck comprising a handle, a steering wheel not mechanically connected to the handle, a handle steering angular velocity detector for detecting the steering angular velocity ωof the handle, and a DC steering motor 15 for steering the steering wheel, a voltage detector 23 is mounted for detecting the electromotive voltage E produced between the armature terminals 22A, 22B of the steering motor 15, and the electric current of a code opposite to that of the electromotive voltage E detected by the voltage detector 23 is allowed to flow between the armature terminals 22A, 22B of the motor 15 when the operation of the handle is approximately stopped, and the steering angular velocity ω of the handle is not changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steering control device for a forklift, and more particularly to a steering control device in which a steering wheel and a steered wheel are not mechanically connected.

[0002]

2. Description of the Related Art Conventionally, as a steering device for a vehicle such as a forklift, a steering motor (hereinafter referred to as a motor 15) is detected based on the angular speed at which the driver rotates the steering wheel when the driver operates the steering wheel. There is known an electric power steering device that drives a steering wheel to steer a steered wheel. Among such electric power steering devices,
The type in which the steering wheel and the steered wheels are not mechanically connected is hereinafter referred to as a free EPS device. FIG. 6 shows a configuration diagram of a conventional free EPS device. In the figure, a free EPS device is a steering wheel 9 operated by a driver.
And a steering wheel operating angular velocity detector 14 for detecting an angular velocity ω (hereinafter referred to as steering angular velocity ω) when operating the steering wheel 9. Further, the free EPS device includes a steered wheel 5 (hereinafter, referred to as a tire 5) and a motor 15 for steering the tire 5.

[0003] A controller 1 for controlling the free EPS device is connected to a steering wheel angular velocity detector 14 and calculates a steering wheel angular velocity ω based on a detection signal of the steering wheel angular velocity detector 14. Then, the controller 1 outputs a torque command value V having a positive correlation with the steering wheel angular velocity ω to the drive circuit 2 for driving the motor 15, and rotates the motor 15 with the specified torque so that the tire 5
Steering.

[0004]

However, the above-mentioned prior art has the following problems. According to the prior art, the torque is applied to the motor 15 during running without operating the steering wheel during running (hereinafter referred to as steering wheel fixed running) so as to run straight or run at a curve with a constant curvature. No current flows because the command value V is not output. Therefore, the motor 15 is in a rotatable state, and when the tire 5 rides on unevenness of the road surface during traveling and receives an external force, the tire 5 rotates and the traveling direction of the vehicle is bent. Moreover, in the free EPS device, since the handle 9 is not mechanically connected to the tire 5, the handle 9 cannot prevent the tire 5 from rotating. As a result, there is a problem that the tire 5 fluctuates left and right, and the forklift meanders or deviates from an intended course.

The present invention has been made in view of the above problems, and has as its object to provide a steering control device capable of running stably without the tires freely rotating even when the steering wheel is not operated. And

[0006]

In order to achieve the above object, a first aspect of the present invention provides a steering wheel for steering a forklift, a steering wheel not mechanically connected to the steering wheel, and a steering angular velocity of the steering wheel. Switching to perform drive control of the steering motor including the rotation direction by turning on and off each switch according to a torque command value to be input and a DC steering motor to steer the steering wheel. In a forklift steering control device including a drive circuit having a circuit and a controller for calculating a torque command value in accordance with the operating angular velocity of the steering wheel and outputting the torque command value to the drive circuit to control the steered wheels, the steering wheel A voltage detector for detecting an electromotive voltage generated between armature terminals of the steering motor when rotated by the controller; During steering operation there is no change in the manipulating angular velocity of the steering wheel and substantially stopped, it is flowing the detected electromotive voltage opposite sign of the current of the voltage detector between the motor armature terminals.

According to the first invention, the voltage between the armature terminals of the motor is detected, and if a voltage is generated between the armature terminals when the handle is not operated, the generated voltage is canceled. Thus, the current is caused to flow between the armature terminals of the motor. That is, when an external force is applied to move the tire, a voltage is generated between armature terminals for inputting current to the motor due to the electromotive force of the motor. At this time, if the steering wheel is not operated, the controller determines that the tire has been rotated by the external force. And
By causing a current to flow between the armature terminals of the motor in such a direction as to cancel this electromotive voltage, it is possible to suppress the tire from rotating. Then, even if the tire is rotated by a strong external force, it can be returned to the original angle by flowing a current between the armature terminals of the motor so as to rotate the rotated tire in the opposite direction. Thereby, even when the steering wheel is not operated, the running can be continued without the tire rotating by the external force, so that the stable running can be achieved.

According to a second aspect of the present invention, in the steering control device for a forklift according to the first aspect of the present invention, the magnitude of the current flowing between the armature terminals of the motor is substantially proportional to the electromotive voltage.

According to the second aspect, a current substantially proportional to the electromotive voltage flows between the armature terminals of the motor. That is, the electromotive voltage generated between the armature terminals is substantially proportional to the angular velocity of the tire rotated by the external force (that is, the angular velocity of the motor). Therefore, by flowing a current approximately proportional to the magnitude of the electromotive force in the reverse direction to the motor, the same resistance to the strength of the rotation due to the external force of the tire is generated, and the rotation of the tire is adjusted to a suitable level. Now you can stop. Also, even if the tire is rotated by a strong external force, the angle of rotation of the tire is approximately proportional to the electromotive voltage, so by flowing a current proportional to this electromotive voltage to the motor, the tire can be accurately adjusted to the original angle. It is possible to return. Thereby, even when the steering wheel is not operated, the running can be continued without the tire rotating by the external force, so that the stable running can be achieved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings. In each embodiment, the same elements as those in the drawings used in the description of the related art are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 shows a configuration diagram of a free EPS apparatus according to an embodiment. In FIG. 1, the free EPS device includes a steering wheel 9 operated by a driver, and a steering wheel angular velocity detector 14 that detects a steering angular velocity ω when the driver operates the steering wheel 9. A handle shaft 10 extends from the center of the handle 9, and a chain 13 is wound between a first sprocket 11 fixed to the shaft end and a second sprocket 12 provided near the first sprocket 11. Is equipped. 2nd sprocket 1
At the center of 2, a handle operation angular velocity detector 14 is attached. A first gear 16 is fixed to an end of a motor 15 that steers the tire 5, and a second gear 17 meshes with the first gear 16. A bracket 20 for transmitting its rotation to the tire 5 is fixed to the second gear 17, and the tire 5 is rotatably attached to an end of the bracket 20. The steering wheel angular velocity ω is input as a detection signal from the steering wheel operating angular velocity detector 14 to the controller 1 that controls the free EPS device. Controller 1
A predetermined calculation is performed based on the steering wheel angular velocity ω to calculate a torque command value V for driving the motor 15, and the torque command value V is output to the drive circuit 2 for driving the motor 15. At this time, the controller 1 makes the torque command value V have a positive correlation with the steering wheel angular velocity ω,
It is particularly preferred that the two be approximately proportional.

FIG. 2 shows an example of the drive circuit 2 in the present embodiment. As shown in the figure, the drive circuit 2 includes a DC power supply 6 and a switching circuit 21 having an H-type bridge structure having, for example, first to fourth switches Q1 to Q4. The switches Q1 to Q4 are semiconductor switching elements such as transistors, for example, and have reverse-biased diodes D1 to D4 in parallel. Further, the drive circuit 2 includes a PWM generation circuit 7 that generates a PWM signal whose duty is substantially proportional to the torque command value V received from the controller 1. This PW
An M signal is applied to each of the switches Q1 to Q4 to switch each of the switches Q1 to Q4.
By turning on / off 1 to Q4, the motor 15 rotates with a torque substantially proportional to the duty of the PWM signal,
The tire 5 is steered. In the figure, switches Q1, Q
When the switch 4 is on and the switches Q2 and Q3 are off, a current flows to the motor 15 leftward in the figure, and the motor 15 rotates, for example, clockwise. Conversely, switch Q2
When the switch Q3 is on and the switches Q1 and Q4 are off, a current flows to the motor 15 leftward in FIG.
Rotates counterclockwise.

At this time, between the armature terminals 22A and 22B for supplying a current to the motor 15, there are provided armature terminals 22A and 22B.
A voltage detector 23 for measuring a voltage generated between the terminals 22B (hereinafter referred to as an electromotive voltage E) is connected. This voltage detector is preferably, for example, an input / output insulated differential amplifier, and outputs the measured electromotive voltage E of the motor 15 to the controller 1. When the motor 15 is rotated by a steering command from the controller 1, a current based on the PWM signal flows between the input armature terminals 22A and 22B of the motor 15, and an electromotive voltage E is generated. On the other hand, when the tire 5 is rotated by an external force, an electromotive force is generated between the armature terminals 22A and 22B of the motor 15 and is substantially proportional to the rotation angular velocity, and an electromotive voltage E is generated. That is, when the motor 15 rotates, the armature terminals 22A, 22B
An electromotive voltage E is generated in between. Therefore, by detecting this electromotive voltage E by the voltage detector 23, the controller 1 can detect that the motor 15 is rotating.

FIG. 3 shows a flowchart for suppressing the rotation of the motor 15 so that the tire 5 is not moved by an external force when the steering wheel 9 is not operated and the steering wheel angular velocity ω = 0. FIG. 4 shows the relationship between the armature terminal voltage E and the torque command value V output by the controller 1. In the following flowchart, each step number is represented by adding S to it. Further, only the case where the electromotive voltage E is positive will be described, but the same applies to the case where the electromotive voltage E is negative.

As described above, the controller 1 can detect the rotation of the motor 15 based on the output of the voltage detector 23 during traveling. Based on this detection, the controller 1 determines whether the rotation of the motor 15 is due to the tire 5 being moved by an external force (S
1). For example, if the steering wheel 9 is not operated and the motor 15 rotates in spite of “the steering wheel angular velocity ω ≒ 0”, it is determined that the electromotive voltage E is generated because the tire 5 is moved by the external force. it can. In S1, if the tire 5 has not been moved by the external force (it is rotation by normal steering), the controller 1 performs normal steering control (S2) and returns to S1. When it is determined in S1 that the tire 5 has been moved by an external force,
The controller 1 compares the magnitude of the electromotive voltage E with a predetermined threshold value E1 (S3), and when the electromotive voltage E is less than the threshold value E1, based on a predetermined straight line L having a gradient m, the electromotive voltage E Is output (S4).
If the electromotive voltage is equal to or larger than the threshold value E in S3, the torque command value V = Vmax (constant value) is output (S5). Then, the PWM generation circuit 7 of the drive circuit 2 outputs a PWM signal having a duty substantially proportional to the input torque command value V to turn on / off each of the switches Q1 to Q4 to drive the motor 15 (S6). Return to S1.

FIG. 5 shows an example of the operation of the switching circuit 21 at this time. As shown in the figure, for example, when a positive electromotive voltage E is generated on the right armature terminal 22B side when the left armature terminal 22A side of the motor 15 is set to zero potential, the motor 15 Is rotating counterclockwise. Accordingly, the controller 1
Outputs a torque command value V having a sign such that a current flows rightward in the figure so that the motor 15 rotates clockwise. For example, at this time, the switch Q1 is turned on and the switch Q1 is turned on.
2. Turn off Q3, and apply a PWM signal with the duty determined in the above procedure to the switch Q4. As a result, a clockwise rotating force is generated in the motor 15 to suppress the rotation caused by the tire 5. The torque command value V instructed to the motor 15 is substantially proportional to the electromotive voltage E generated between the armature terminals 22A and 22B of the motor 15, and the electromotive voltage E is the angular velocity when the tire 5 is rotated. Is approximately proportional to Therefore, a resistance force that is always substantially proportional to the force for rotating the tire acts on the motor 15. At this time, the rotational force and the resistance force are equal,
By determining the slope m of the straight line L between the electromotive voltage E and the torque command value V, it is possible to generate a resistance force substantially equal to the force for rotating the tire 5.

As described above, according to this embodiment, when the tire 5 is rotated by an external force, the motor 1
5 is provided with a voltage detector 23 for detecting an electromotive voltage E generated between the armature terminals 22A and 22B. Thereby, the controller 1 can detect that the motor 15 is rotating. Then, the controller 1 controls the drive circuit 2
Output a predetermined torque command value V to the motor 1
Even if a failure occurs in which the 5 does not rotate, the failure can be detected. Therefore, the vehicle is less likely to run in a failure state, and the reliability of the steering control device is improved.

When the tire 5 starts to rotate due to an external force, the fact is detected and the armature terminal 22 of the motor 15 is detected.
A current flows in the opposite direction to the rotation direction between A and 22B.
Thereby, the motor 15 becomes a resistance against the rotational force,
The angle at which the tire 5 rotates due to external force becomes very small. Accordingly, the occurrence of the meandering of the forklift and the deviation of the forklift from the course due to the movement of the tire 5 during traveling is reduced. At this time, the magnitude of the current flowing between the armature terminals 22A and 22B is made substantially proportional to the voltage E between the armature terminals. Electromotive force E generated between armature terminals 22A and 22B
Is substantially proportional to the angular velocity of the tire 5 rotated by an external force, that is, the angular velocity of the motor 15. Therefore, by flowing a current substantially proportional to the magnitude of the electromotive voltage E to the motor 15 in the reverse direction, the same resistance as the rotation strength due to the external force of the tire 5 is generated in the motor 15, 5 can be stopped with a suitable strength. Therefore, even when the steering wheel 9 is operated without operating the steering wheel 9, the tire 5 is less likely to rotate freely due to an external force, and stable steering and traveling can be performed even with a free EPS device.

Furthermore, despite the resistance of the motor 15, the tire 5 may be rotated by a strong external force. Even in such a case, the generated electromotive force E
Is approximately proportional to the angle of rotation of the tire 5,
The controller 1 can detect how much the tire 5 has rotated based on the intensity of the electromotive voltage E and the time during which the electromotive voltage E is applied. Then, a command is output to the drive circuit 2 based on the angle of rotation of the tire 5, and the motor 1
By rotating the tire 5 by a predetermined angle, it is possible to return the angle of the tire 5 to substantially the same position as before rotation. At this time, by making the current flowing through the motor 15 substantially proportional to the strength of the electromotive voltage E, the tire 5 can be more accurately returned to the original angle. In addition, at this time, the rotation angle of the tire 5 is detected by an electrical device such as the voltage detector 23 instead of using a mechanical detection device. Therefore, since there is no mechanical movable part, the failure of the detection device is small. In addition, the size of the detection device can be small.

Although the embodiment has been described with reference to the case where the handle operation angular velocity detector 14 detects the handle operation angular velocity ω, the invention is not limited to this. For example, a potentiometer may be provided in place of the steering wheel angular velocity detector 14 to detect the angle at which the steering wheel is operated, and a differential operation may be performed inside the controller 1 to calculate the steering wheel angular velocity ω.

The switching circuit 2 in the driving circuit 2
Although the semiconductor switching elements have been described as the first to fourth switches Q1 to Q4 in 1, a mechanical switch may be used as long as the operation speed is sufficiently fast. Further, the switching circuit 21 includes first to fourth switches Q1 to Q4.
However, the present invention is not limited to this, and may be any switching circuit 21 that controls the motor 15 by switching. For example, in FIG. 2, the DC power supplies 6 and 6 are arranged at the positions of the switches Q1 and Q2 except for the DC power
3, a switching circuit 21 for controlling the motor 15 by switching Q4 may be used. Further, the PWM generation circuit 7 has been described as being in the drive circuit 2, but may be in the controller 1.

In the embodiment, the torque command value V is described to be proportional to the electromotive voltage E from the vicinity of "electromotive voltage E = 0", but the present invention is not limited to this. For example, a second threshold value E2 (E2Ｅ0) is provided as shown in FIG.
Is output in the range of −E2 <E <E2, the torque command value V = 0 is output, and E ≧ E2 or E ≦ −E2
Only in the case of, the electromotive voltage E and the torque command value V may be made substantially proportional. In this way, for example, when the electromotive voltage E fluctuates in the vicinity of zero value due to the slight vibration of the tire, the torque command value V is not output in small increments to perform the continuous vibration, and the operation is more stable. It is possible to continue.

In the embodiment, "electromotive voltage E≤E1"
, The torque command value V is made substantially proportional to the electromotive voltage E,
In the case of "electromotive voltage E>E1,""torque command value V = Vma
x ", the cases were clearly divided before and after the threshold value E1,
However, it is not limited to this. For example, while the electromotive voltage E is much smaller than the threshold value E1, the torque command value V is made substantially proportional to the electromotive voltage V. As the electromotive voltage E approaches the threshold value E1, the torque command value V gradually saturates to Vmax. May be approached.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a free EPS device according to an embodiment.

FIG. 2 is a circuit diagram illustrating an example of a driving circuit.

FIG. 3 is a flowchart for suppressing rotation of a motor.

FIG. 4 is a graph showing a relationship between an electromotive voltage and a torque command value.

FIG. 5 is a circuit diagram illustrating the operation of a switching circuit.

FIG. 6 is a configuration diagram of a conventional free EPS device.

[Explanation of symbols]

1: controller, 2: drive circuit, 5: tire, 6: DC power supply, 7: PWM generation circuit, 9: handle, 10: handle shaft, 11: first sprocket, 12: second sprocket, 13: chain, 14 ： Handle angle detector, 1
5: motor, 16: first gear, 17: second gear, 20:
Bracket, 21: switching circuit, 22: armature terminal, 23: voltage detector.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B62D 113: 00 117: 00 F term (Reference) 3D032 CC01 CC34 DA03 DA09 DA65 DC01 DC33 DC34 DD10 EA02 EB11 EC23 EC25 GG06 3D033 CA03 CA17 CA19 CA20 CA21 3F333 AA02 AB13 FA20 FA32 FD08 FE04 FE09 5H001 AC02 AD03 5H530 AA12 BB21 CC20 CD20 CD35 CD40 CE13 DD15

Claims (2)

[Claims] 1. A steering wheel for steering a forklift
(9), a steering wheel (5) that is not mechanically connected to the steering wheel (9), a steering wheel angular velocity detector (14) that detects an operating angular velocity (ω) of the steering wheel (9), and a steering wheel (5) By turning on / off each switch (Q1 to Q4) according to the DC steering motor (15) to steer and the input torque command value (V), the steering motor including the rotation direction is controlled.
A drive circuit (2) including a switching circuit (21) for performing drive control of (15), and a torque command value (V) according to an operation angular velocity (ω) of the handle (9).
And a controller (1) for controlling the steered wheels (5) by outputting to the drive circuit (2), the armature terminals (22A, 22B) of the steering motor (15). ) Is provided with a voltage detector (23) for detecting an electromotive voltage (E) generated between the controller (1), while the steering wheel operation is substantially stopped and the operating angular velocity (ω) of the steering wheel (9) does not change. Voltage detector (2
The current with the opposite sign to the electromotive voltage (E) detected in 3) is
A steering control device for a forklift, wherein the current flows between the armature terminals (22A, 22B). 2. The forklift steering control device according to claim 1, wherein the magnitude of a current flowing between the armature terminals (22A, 22B) of the motor (15) is substantially proportional to the electromotive voltage (E). A steering control device for a forklift.