JP5979687B1 - Steering control device, electric vehicle, and steering control method - Google Patents

Abstract

A steering control device capable of preventing a posture of a vehicle body from being largely changed by a plugging operation is provided. A steering control device (1) for controlling steering of at least one front wheel of a left front wheel (20) or a right front wheel (30) of an electric vehicle (100), wherein one front wheel when a plugging operation is performed is Steering angle fixing control is performed so that the steering angle of one front wheel is returned to the setting angle and fixed when the steering angle exceeds a preset setting angle with reference to the steering angle of one front wheel during forward and backward travel. It is characterized by. [Selection] Figure 1

Description

  The present invention relates to a steering control device, an electric vehicle including the steering control device, and a steering control method.

  Conventionally, a reach-type omnidirectional forklift is known as an electric vehicle equipped with a steering control device (see, for example, Patent Document 1). In the reach-type omnidirectional forklift, the steering control device sets the steering angle of the left front wheel (road wheel) and the right front wheel (road wheel) according to the driving mode selected by the operator and the steering angle of the rear wheel (drive wheel). Independent control enables omnidirectional travel.

  In the reach-type omnidirectional forklift, the deadman brake device applies the brake only to the rear wheel, so that depending on the steering angle of the left front wheel and the right front wheel during the brake operation, the posture of the vehicle body is greatly changed by the brake operation. Specifically, due to inertia and centrifugal force, the left front wheel and the right front wheel roll around the contact point between the rear wheel and the road surface, and the vehicle body rotates. Therefore, in the reach-type omnidirectional forklift, at the time of braking, at least one of the left front wheel or the right front wheel is rotated (steered) in a direction opposite to the direction in which the vehicle body rotates and is controlled at a predetermined angle. In this way, the vehicle body is prevented from rotating by generating a frictional force with the road surface.

  The steering angle fixing control for the front wheels will be specifically described with reference to FIG. The reach-type omnidirectional forklift is assumed to be traveling in the lateral movement mode as shown in FIG. In the case of the lateral movement mode, the steering control device sets the steering angles of the rear wheel 40, the left front wheel 20 and the right front wheel 30 to 90 °. In the lateral movement mode, when the operator tilts the accelerator lever forward from the neutral position, the vehicle body 10 moves to the left, and when the operator tilts the accelerator lever backward from the neutral position, the vehicle body 10 moves to the right.

When the steering operation is performed by the operator while the vehicle body 10 is moving in the left direction, the steering control device causes the steering angles of the rear wheel 40, the left front wheel 20, and the right front wheel 30 to be shown in FIG. To control. That is, the steering control device is configured to steer the rear wheels 40 to the steering angle corresponding to the operation amount of the steering, to fix the steering angle of the right front wheel 30 to 90 °, and extension H _R of the rotary shaft of the right front wheel 30 the intersection point P of the extension line H _F of the rotating shaft of the rear wheel 40 so as to pass the extended line H _L of the rotary shaft of the left front wheel 20, to steer the left front wheel 20. At this time, the intersection P becomes the turning center of the vehicle body 10, and the frictional force (slip) of the rear wheel 40, the left front wheel 20 and the right front wheel 30 is minimized, so that smooth turning is possible. Thus, the steering so that the extension line H _L of the rotary shaft of the left front wheel 20, and the extension line H _R of the rotary shaft of the right front wheel 30, and the extension line H _F of the rotating shaft of the rear wheel 40 intersect at one point Controlling the angle is called steering control by Ackermann steering.

When the brake operation by the operator is performed while the steering control by the Ackermann steering is performed, the steering control device performs the steering angle fixing control on the left front wheel 20 as shown in FIG. That is, the steering control device, such that the extension line H _F of the rotating shaft of the extension line H _R and the rear wheel 40 of the rotary shaft of the extension line H _L and the right front wheel 30 of the rotary shaft of the left front wheel 20 do not intersect at one point Further, the steering angle of the left front wheel 20 is steered to a preset setting angle (for example, 60 °) and fixed. Thereby, since a frictional force is generated between the left front wheel 20 and the road surface, the vehicle body 10 can be prevented from rotating due to a brake operation.

JP-A-5-246347

  By the way, in the reach type omnidirectional forklift, when the rear wheel 40 is mechanically locked by a brake operation and the vehicle body 10 is stopped, the vehicle body 10 is stopped by regenerative braking of the rear wheel 40 by a plugging operation. There are many.

  However, in the conventional reach type omnidirectional forklift, the steering angle fixing control is performed only at the time of braking operation, and the steering angle fixing control is not performed at the time of plugging operation. There was a fear.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a steering control device, an electric vehicle, and a steering device that can prevent the posture of the vehicle body from greatly changing due to a plugging operation. It is to provide a control method.

In order to solve the above problems, a steering control device according to the present invention includes:
In an electric vehicle including a left front wheel and a right front wheel and a rear wheel steered by a steering operation, the rear wheel is regeneratively braked by a plugging operation, and the rotation of the rear wheel is stopped by a brake operation. A steering control device for controlling steering of at least one front wheel of the front wheels,
When the one front wheel at the time of the plugging operation is steered beyond a preset angle set based on the steering angle of the one front wheel at the time of forward / backward traveling of the electric vehicle, Steering angle fixing control is performed to return and fix the steering angle to the set angle.

The steering control device
During the steering angle fixing control, the steering angle fixing control can be canceled when the traveling speed of the electric vehicle being decelerated is lower than a preset set speed or when the electric vehicle stops. .

The steering control device
The plugging operation includes an accelerator reversing operation for changing the direction of the electric vehicle and an accelerator OFF operation for stopping the electric vehicle,
In the case of the accelerator reversing operation, the steering angle fixing control is canceled when the traveling speed is lower than the set speed,
In the case of the accelerator OFF operation, the steering angle fixing control can be released when the electric vehicle stops.

In order to solve the above problems, an electric vehicle according to the present invention is:
An electric vehicle comprising a left front wheel and a right front wheel and a rear wheel steered by a steering operation, wherein the rear wheel is regeneratively braked by a plugging operation, and rotation of the rear wheel is stopped by a brake operation;
A steering control device for controlling at least one front wheel of the left front wheel or the right front wheel;
A plugging operation detecting means for detecting the plugging operation;
First angle detection means for detecting a steering angle of the left front wheel;
Second angle detecting means for detecting a steering angle of the right front wheel;
First steering means for steering the left front wheel under the control of the steering control device;
Second steering means for steering the right front wheel under the control of the steering control device;
With
The steering control device includes:
Based on the detection result of the plugging operation detection means and the detection result of at least one of the first angle detection means or the second angle detection means, the steering angle of the one front wheel during the plugging operation is the electric vehicle. Determining whether or not it exceeds a preset angle based on the steering angle of the one front wheel during forward / backward travel of the vehicle,
Steering angle fixing control for controlling the first steering means or the second steering means to fix the steering angle of the one front wheel back to the set angle when it is determined that the set angle is exceeded. It is characterized by performing.

The above electric car
A rotation detecting means for detecting a rotation amount of a traveling motor for rotating the rear wheel;
The steering control device includes:
Calculate the traveling speed of the electric vehicle based on the detection result of the rotation detection means,
During the steering angle fixing control, the steering angle fixing control can be canceled when the traveling speed of the electric vehicle being decelerated is lower than a preset set speed or when the electric vehicle stops. .

In order to solve the above problems, a steering control method according to the present invention includes:
In an electric vehicle that includes a steering control device, a left front wheel and a right front wheel, and a rear wheel that is steered by a steering operation, the rear wheel is regeneratively braked by a plugging operation, and rotation of the rear wheel is stopped by a brake operation. The steering control device controls the steering of at least one front wheel of the left front wheel or the right front wheel,
A first step of comparing a steering angle of the one front wheel at the time of the plugging operation with a set angle set in advance based on the steering angle of the one front wheel at the time of forward and backward movement of the electric vehicle;
And a second step of performing a steering angle fixing control for fixing the steering angle back to the set angle when the steering angle of the one front wheel during the plugging operation exceeds the set angle. Features.

The steering control method is
Third step of releasing the steering angle fixing control when the traveling speed of the electric vehicle being decelerated is lower than a preset set speed or when the electric vehicle stops during the steering angle fixing control. Can be configured to include.

  According to the present invention, it is possible to provide a steering control device, an electric vehicle, and a steering control method capable of preventing the posture of the vehicle body from being largely changed by a plugging operation.

It is a lineblock diagram of an electric car (reach type omnidirectional forklift) concerning a 1st embodiment of the present invention. It is a figure which shows the relationship between the steering control apparatus which concerns on 1st Embodiment of this invention, and various detection means. It is a flowchart of the steering control method which concerns on 1st Embodiment of this invention. It is a flowchart of the steering control method which concerns on 2nd Embodiment of this invention. It is a figure which shows a series of driving | running | working states of the conventional reach type omnidirectional forklift, (A) is a figure at the time of left movement, (B) is a figure at the time of steering operation, (C) is a figure at the time of brake operation. .

  Hereinafter, embodiments of a steering control device, an electric vehicle, and a steering control method according to the present invention will be described with reference to the accompanying drawings. As an electric vehicle according to the present invention, a reach type omnidirectional forklift will be described as an example. The front-rear, left-right, and up-down directions are based on the reach type omnidirectional forklift vehicle body (in the steering control device, the state mounted on the vehicle body) unless otherwise specified.

[First Embodiment]
FIG. 1 shows a reach type omnidirectional forklift (hereinafter referred to as a forklift) 100 according to a first embodiment of the present invention. The forklift 100 includes the steering control device 1 according to the first embodiment of the present invention inside the vehicle body 10.

  The forklift 100 includes a pair of left and right straddle legs 2 extending to the front side of the vehicle body 10 and a carriage 3 that moves in the front-rear direction along the straddle legs 2. A pair of left and right mast devices 4 are erected on the carriage 3 in the vertical direction. The mast device 4 is provided with a pair of left and right forks 5 that can be raised and lowered. Further, the forklift 100 includes a driver's seat 6 at the right rear portion of the vehicle body 10 that allows an operator to get on and off while standing. A deadman brake device 7 is provided on the floor of the driver's seat 6.

  The left straddle leg 2 includes a left front wheel (road wheel) 20, a steering motor 21, a bracket 22 that rotatably supports the left front wheel 20, a transmission member 23 made of, for example, a gear, and a first made of, for example, a potentiometer. Angle detection means 24 is provided. The steering motor 21, the bracket 22, and the transmission member 23 correspond to the “first steering means” of the present invention. When the steering motor 21 is rotationally driven under the control of the steering control device 1, the power of the steering motor 21 is transmitted to the bracket 22 through the transmission member 23, and the left front wheel 20 turns by turning the bracket 22. The first angle detector 24 detects the turning angle of the bracket 22 and outputs a signal related to the turning angle to the steering control device 1.

  The right straddle leg 2 includes a right front wheel (road wheel) 30, a steering motor 31, a bracket 32 that rotatably supports the right front wheel 30, a transmission member 33 made of, for example, a gear, and a second portion made of, for example, a potentiometer. Angle detection means 34 is provided. The steering motor 31, the bracket 32, and the transmission member 33 correspond to the “second steering means” of the present invention. When the steering motor 31 is rotationally driven under the control of the steering control device 1, the power of the steering motor 31 is transmitted to the bracket 32 via the transmission member 33, and the right front wheel 30 is turned by turning the bracket 32. The second angle detection means 34 detects the turning angle of the bracket 32 and outputs a signal related to the turning angle to the steering control device 1.

  A rear wheel (drive wheel) 40, a travel motor 41, a steering motor 42, third angle detection means 43 including, for example, a potentiometer, and a drive device (not shown) are provided at the left rear portion of the vehicle body 10. Yes. The travel motor 41 and the steering motor 42 are independently connected to the rear wheel 40 via a drive device. When the traveling motor 41 is rotationally driven under the control of the steering control device 1, the power of the traveling motor 41 is transmitted to the rear wheel 40 via the drive device, and the rear wheel 40 rotates forward or backward. When the steering motor 42 is driven to rotate under the control of the steering control device 1, at least a part of the drive device turns and the rear wheel 40 turns. The third angle detection unit 43 detects the turning angle of the drive device and outputs a signal related to the turning angle to the steering control device 1. A caster wheel (not shown) is provided at the right rear portion of the vehicle body 10 in order to ensure the running stability of the vehicle body 10.

  The forklift 100 includes a steering handle 8 for steering the rear wheel 40 and levers 9 on the upper surface of the vehicle body 10. The steering control device 1 steers the rear wheel 40 by rotating the steering motor 42 according to the steering operation amount of the steering handle 8. The levers 9 include a cargo handling lever (lift lever, tilt lever and reach lever) and an accelerator lever. When an accelerator ON operation for tilting the accelerator lever at the neutral position forward or backward is performed, the steering control device 1 rotates the rear wheel 40 forward when it tilts forward and reversely rotates the rear wheel 40 when it tilts backward. Let When an accelerator reversing operation is performed in which the accelerator lever in the forward tilt state is tilted rearward or the accelerator lever in the rear tilt state is tilted forward, the steering control device 1 causes the rear wheel 40 to regeneratively brake and The rotation direction of the wheel 40 is changed. When an accelerator OFF operation for returning the accelerator lever in the forward tilt state or the rear tilt state to the neutral position is performed, the steering control device 1 regeneratively brakes the rear wheel 40 to stop the rotation of the rear wheel 40.

  The forklift 100 includes a mode switching button 11 for switching a traveling mode on the upper surface of the vehicle body 10. The traveling mode includes a standard mode, a small turn mode, a lateral movement mode, an oblique movement mode, and the like. The standard mode is a mode that makes a spin turn around the center of the vehicle body 10 and enables a change of direction on the spot. The small turn mode is a mode in which the vehicle turns around the side surface of the vehicle body. The lateral movement mode is a mode that moves in the left-right direction. The oblique movement mode is a mode that enables oblique movement while arbitrarily changing the posture of the vehicle body 10.

  The steering control device 1 is configured by a microcomputer, for example. The steering control device 1 performs steering control for controlling the steering of the rear wheel 40, the left front wheel 20, and the right front wheel 30 in accordance with the travel mode selected by the operator and the steering operation amount of the steering handle 8. For example, when the lateral movement mode is selected by the operator, the steering control device 1 steers the rear wheel 40, the left front wheel 20, and the right front wheel 30 so that the steering angle becomes 90 °. When the steering operation is performed in the lateral movement mode, the steering control device 1 steers the rear wheel 40 to the steering angle corresponding to the steering operation amount, and fixes the steering angle of the right front wheel 30 to 90 °. The left front wheel 20 is steered so that the extension line of the rotation axis of the left front wheel 20 passes through the intersection of the extension line of the rotation axis of the right front wheel 30 and the extension line of the rotation axis of the rear wheel 40.

  Further, the steering control device 1 performs the steering angle fixing control under a certain condition. Steering angle fixing control according to the present embodiment refers to at least one of the left front wheel 20 or the right front wheel 30 by a plugging operation during a plugging operation for regenerative braking of the rear wheel 40 (accelerator reversing operation or accelerator OFF operation). The control is to rotate (steer) in a direction opposite to the direction in which 10 rotates and to fix it at a preset angle. The set angle is a steering angle set with reference to a steering angle when the vehicle body 10 is moving forward and backward, in other words, a steering angle set when the steering angle when the vehicle body 10 is moving forward and backward is 0 °. In the present embodiment, the setting angle for the left front wheel 20 is set to 60 ° counterclockwise (counterclockwise), and the setting angle for the right front wheel 30 is set to 60 ° clockwise (clockwise). In the present embodiment, the steering angle fixing control is performed on the left front wheel 20 in the lateral movement mode, and the steering angle fixing control is performed on the left front wheel 20 and the right front wheel 30 in the oblique movement mode.

Next, a steering control method according to this embodiment will be described. The steering control method according to the present embodiment is performed by the steering control device 1, and mainly,
(1) a first step of comparing the steering angle of one front wheel of the left front wheel 20 or the right front wheel 30 during the plugging operation with the set angle described above;
(2) a second step of performing a steering angle fixing control for fixing the steering angle back to the setting angle when the steering angle of the one front wheel during the plugging operation exceeds the setting angle;
(3) a third step of canceling the steering angle fixing control when the traveling speed of the vehicle body 10 being decelerated is lower than a preset set speed or when the vehicle body 10 is stopped during the steering angle fixing control; ,
Is included.

  With reference to FIG. 2 and FIG. 3, the steering control method according to the present embodiment will be described by taking as an example the case where the lateral movement mode is selected. Here, it is assumed that the vehicle body 10 is moved to the left by an accelerator ON operation (an operation in which the accelerator lever is tilted forward).

  As shown in FIG. 3, when the vehicle body 10 starts to move to the left, the steering control device 1 determines whether or not a brake operation has been performed (S1). The deadman brake device 7 is provided with a brake operation detection means (for example, a potentiometer) 12 for detecting the depression amount of the brake pedal. The steering control device 1 determines that there is a brake operation when the pedal depression amount exceeds a predetermined threshold, and determines that there is no brake operation when the pedal depression amount is less than the predetermined threshold.

  The steering control device 1 that has determined that there is no brake operation determines whether or not a plugging operation (accelerator reverse operation or accelerator OFF operation) has been performed (S2). The accelerator lever is provided with accelerator operation detection means (for example, a potentiometer) 13 for detecting the tilt angle of the accelerator lever. For example, when the neutral position of the accelerator lever tilt angle is 0 °, the forward tilt side is a positive angle, and the rear tilt side is a negative angle, the steering control device 1 performs the accelerator reversing operation when the tilt angle is a negative angle. It is determined that the accelerator OFF operation is performed when the tilt angle is 0 °, and it is determined that the accelerator reversal operation and the accelerator OFF operation are not performed when the tilt angle is a positive angle. The accelerator operation detection means corresponds to the “plugging operation detection means” of the present invention.

  The steering control device 1 that has determined that the accelerator reversing operation and the accelerator OFF operation have not been performed determines whether or not the brake operation has been performed again (S1). Note that the determination in step S1 and the determination in step S2 may be performed in reverse order or simultaneously.

  In the steering control device 1 that has determined that the accelerator reversing operation has been performed, does the steering angle of the left front wheel 20 at the time of the accelerator reversing operation exceed a set angle (60 ° counterclockwise with respect to the steering angle during forward / rearward travel)? Is determined based on the steering angle of the left front wheel 20 (the turning angle of the bracket 22) detected by the first angle detector 24 (S3). In the present embodiment, the steering angle of the left front wheel 20 matches the turning angle of the bracket 22.

  When it is determined that the steering angle of the left front wheel 20 exceeds the set angle, the steering control device 1 starts the steering angle fixing control for the left front wheel 20 (S4). On the other hand, when the steering control device 1 determines that the steering angle of the left front wheel 20 is equal to or smaller than the set angle, the steering control device 1 does not start the steering angle fixing control. For example, when a right turn is performed in the lateral movement mode, the steering angle of the left front wheel 20 may be equal to or less than a set angle.

  The steering control device 1 that has started the steering angle fixing control with respect to the left front wheel 20 outputs a drive signal to the steering motor 21 that turns the left front wheel 20 and fixes the steering angle of the left front wheel 20 back to the set angle. At this time, the steering angle of the right front wheel 30 remains 90 °, but when the steering angle of the left front wheel 20 becomes 60 °, a frictional force is generated between the left front wheel 20 and the road surface. This frictional force can prevent the vehicle body 10 from rotating around the contact point between the rear wheel 40 and the road surface.

  A travel motor 41 for rotating the rear wheel 40 is provided with a rotation detection means (for example, a bearing sensor) 14 for detecting the rotation amount of the travel motor 41. The steering control device 1 that has started the steering angle fixing control calculates the traveling speed of the vehicle body 10 based on the rotation amount of the traveling motor 41, and the traveling speed is set in advance to a first set speed V1 (in this embodiment, 1 [km / h]) is determined (S5). The traveling speed is positive in the direction in which the vehicle body 10 is traveling when the steering angle fixing control is started.

  The steering control device 1 repeats the determination in step S5 until it determines that the traveling speed has fallen below the first set speed V1. The steering control device 1 that has determined that the traveling speed has fallen below the first set speed V1 cancels the steering angle fixing control (S6). As a result, the left front wheel 20 is steered so that the steering angle of the left front wheel 20 changes from the set angle to the angle corresponding to the travel mode during deceleration, so that smooth reacceleration is possible when the direction is changed. Here, the angle corresponding to the travel mode is basically 90 ° in the lateral movement mode, but when the steering operation is performed, the extension line of the rotating shaft of the right front wheel 30 and the rear wheel 40 This is the angle when the extension line of the rotation axis of the left front wheel 20 passes through the intersection with the extension line of the rotation axis.

  In step S2, the steering control device 1 that has determined that the accelerator OFF operation has been performed determines whether or not the steering angle of the left front wheel 20 exceeds the set angle, similarly to step S3 (S13). The steering control device 1 starts the steering angle fixing control for the left front wheel 20 when it is determined that the setting angle is exceeded (S14), and does not start the steering angle fixing control when it is determined that the angle is equal to or less than the setting angle.

  The steering control device 1 that has started the steering angle fixing control returns and fixes the steering angle of the left front wheel 20 to the set angle, and determines whether or not the vehicle body 10 has stopped based on the detection result of the rotation detection means 14. (S15). For example, when the rotation amount of the travel motor 41 detected by the rotation detection unit 14 becomes 0, the steering control device 1 determines that the vehicle body 10 has stopped, and cancels the steering angle fixing control (S16). Thus, the braking performance and safety can be improved by performing the steering angle fixing control until the vehicle body 10 stops.

  In step S1, the steering control device 1 that has determined that there is a brake operation determines whether or not the steering angle of the left front wheel 20 exceeds the set angle, similarly to steps S3 and S13 (S23). The steering control device 1 starts the steering angle fixing control for the left front wheel 20 when it is determined that the set angle is exceeded (S24), and does not start the steering angle fixing control when it is determined that the angle is equal to or less than the set angle.

  The steering control device 1 that has started the steering angle fixing control returns and fixes the steering angle of the left front wheel 20 to the set angle, and determines whether or not the vehicle body 10 has stopped based on the detection result of the rotation detection means 14. (S25). When it is determined that the vehicle body 10 has stopped, the steering control device 1 cancels the steering angle fixing control (S26). Instead of step S25, it is determined whether the brake operation has been released based on the detection result of the brake operation detection means 12, and when it is determined that the brake operation has been released, the steering angle fixing control is released. Also good.

[Second Embodiment]
The steering control device, the forklift, and the steering control method according to the second embodiment of the present invention differ from the first embodiment only in the release condition of the steering angle fixing control. Therefore, in this embodiment, the same reference numerals as those in the first embodiment are used. Further, the description of the steering control device 1 and the forklift 100 according to the present embodiment is omitted.

  The steering control method flow in this embodiment is as shown in FIG. That is, the difference from the first embodiment is that the determination of step S5 'is performed instead of the determination of step S5, and the determination of step S15' is performed instead of the determination of step S15.

  In step S <b> 5 ′, the steering control device 1 determines whether the vehicle body 10 has stopped based on the detection result of the rotation detection unit 14. The steering control device 1 determines that the vehicle body 10 has stopped when the rotation amount of the travel motor 41 detected by the rotation detection means 14 becomes 0, and cancels the steering angle fixing control (S6). Thus, by performing the steering angle fixing control until the vehicle body 10 stops, the braking performance and safety at the time of turning can be improved.

  In step S15 ′, the steering control device 1 calculates the traveling speed of the vehicle body 10 based on the rotation amount of the traveling motor 41, and the traveling speed is set to a second set speed V2 (in this embodiment, 1 [ km / h]). The steering control device 1 that has determined that the traveling speed has fallen below the second set speed V2 cancels the steering angle fixing control (S16). As a result, the left front wheel 20 is steered so that the steering angle of the left front wheel 20 changes from the set angle (60 °) to the angle (for example, 90 °) according to the travel mode when decelerating. When the accelerator ON operation is performed immediately before starting, smooth reacceleration is possible.

  The embodiments of the steering control device, the electric vehicle, and the steering control method according to the present invention have been described above, but the present invention is not limited to the above embodiments.

  In each of the above-described embodiments, the reach-type omnidirectional forklift 100 is described as an example of the electric vehicle, but the electric vehicle according to the present invention includes a left front wheel, a right front wheel, and a rear wheel that is steered by a steering operation. It is sufficient if the rear wheel is regeneratively braked by the plugging operation and the rotation of the rear wheel is stopped by the brake operation. For example, a forklift other than the reach type omnidirectional forklift 100 may be used.

  In each of the embodiments described above, the steering control device 1 that performs normal steering control (for example, steering control by Ackermann steering) and steering angle fixing control is used as the steering control device, but the steering control device according to the present invention is used. Is sufficient if it performs at least steering angle fixing control. When the steering control device according to the present invention performs only the steering angle fixing control, a separate device for performing normal steering control is required.

  The cancellation condition of the steering angle fixing control can be changed as appropriate. In the first embodiment, when the traveling speed falls below the first set speed V1 during the accelerator reversing operation, or when the vehicle body 10 stops during the accelerator OFF operation, in the second embodiment, the vehicle body 10 stops during the accelerator reversing operation. Or when the travel speed falls below the second set speed V2 during the accelerator OFF operation, for example, when the travel speed falls below the first set speed V1 during the accelerator reverse operation or when the accelerator OFF operation is performed. May be lower than the second set speed V2, or may be when the vehicle body 10 is stopped during the accelerator reversing operation, or when the vehicle body 10 is stopped during the accelerator OFF operation.

  In the above embodiment, the setting angle for the left front wheel 20 is set to 60 ° counterclockwise (counterclockwise), and the setting angle for the right front wheel 30 is set to 60 ° clockwise (clockwise). The set angle can be appropriately changed as long as the frictional force is generated between the road surface and the road surface during the plugging operation or the brake operation.

DESCRIPTION OF SYMBOLS 1 Steering control apparatus 2 Straddle leg 3 Carriage 4 Mast apparatus 5 Fork 6 Driver's seat 7 Deadman brake apparatus 8 Steering handle 9 Lever 10 Car body 11 Mode switch button 12 Brake operation detection means 13 Acceleration operation detection means (plugging operation detection means)
14 Rotation detection means 20 Left front wheel (road wheel)
21 Steering motor 22 Bracket 23 Transmission member 24 First angle detection means 30 Right front wheel (road wheel)
31 Steering motor 32 Bracket 33 Transmission member 34 Second angle detecting means 40 Rear wheel 41 Traveling motor 42 Steering motor 43 Third angle detecting means 100 Reach type omnidirectional forklift

Claims (7)

In an electric vehicle including a left front wheel and a right front wheel and a rear wheel steered by a steering operation, the rear wheel is regeneratively braked by a plugging operation, and the rotation of the rear wheel is stopped by a brake operation. A steering control device for controlling steering of at least one front wheel of the front wheels,
When the one front wheel at the time of the plugging operation is steered beyond a preset angle set based on the steering angle of the one front wheel at the time of forward / backward traveling of the electric vehicle, A steering control apparatus for performing steering angle fixing control for fixing the steering angle back to the set angle. In the steering angle fixing control, the steering angle fixing control is canceled when a traveling speed of the electric vehicle being decelerated is lower than a preset set speed or when the electric vehicle stops. The steering control device according to claim 1. The plugging operation includes an accelerator reversing operation for changing the direction of the electric vehicle, and an accelerator OFF operation for stopping the electric vehicle,
In the case of the accelerator reversing operation, the steering angle fixing control is canceled when the traveling speed is lower than the set speed,
The steering control device according to claim 2, wherein in the case of the accelerator OFF operation, the steering angle fixing control is canceled when the electric vehicle stops. An electric vehicle comprising a left front wheel and a right front wheel and a rear wheel steered by a steering operation, wherein the rear wheel is regeneratively braked by a plugging operation, and rotation of the rear wheel is stopped by a brake operation;
A steering control device for controlling at least one front wheel of the left front wheel or the right front wheel;
A plugging operation detecting means for detecting the plugging operation;
First angle detection means for detecting a steering angle of the left front wheel;
Second angle detecting means for detecting a steering angle of the right front wheel;
First steering means for steering the left front wheel under the control of the steering control device;
Second steering means for steering the right front wheel under the control of the steering control device;
With
The steering control device includes:
Based on the detection result of the plugging operation detection means and the detection result of at least one of the first angle detection means or the second angle detection means, the steering angle of the one front wheel during the plugging operation is the electric vehicle. Determining whether or not it exceeds a preset angle based on the steering angle of the one front wheel during forward / backward travel of the vehicle,
Steering angle fixing control for controlling the first steering means or the second steering means to fix the steering angle of the one front wheel back to the set angle when it is determined that the set angle is exceeded. An electric vehicle characterized in that it performs. A rotation detecting means for detecting a rotation amount of a traveling motor for rotating the rear wheel;
The steering control device includes:
Calculate the traveling speed of the electric vehicle based on the detection result of the rotation detection means,
In the steering angle fixing control, the steering angle fixing control is canceled when a traveling speed of the electric vehicle being decelerated is lower than a preset set speed or when the electric vehicle stops. The electric vehicle according to claim 4. In an electric vehicle that includes a steering control device, a left front wheel and a right front wheel, and a rear wheel that is steered by a steering operation, the rear wheel is regeneratively braked by a plugging operation, and rotation of the rear wheel is stopped by a brake operation. The steering control device controls the steering of at least one front wheel of the left front wheel or the right front wheel,
A first step of comparing a steering angle of the one front wheel at the time of the plugging operation with a set angle set in advance based on the steering angle of the one front wheel at the time of forward and backward movement of the electric vehicle;
And a second step of performing a steering angle fixing control for fixing the steering angle back to the set angle when the steering angle of the one front wheel during the plugging operation exceeds the set angle. A characteristic steering control method. Third step of releasing the steering angle fixing control when the traveling speed of the electric vehicle being decelerated is lower than a preset set speed or when the electric vehicle stops during the steering angle fixing control. The steering control method according to claim 6, further comprising:

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