JP4671245B2 - Power steering device - Google Patents

Description

  The present invention relates to a steer-by-wire power steering apparatus that drives a steered wheel in a steering direction in accordance with a turning angle of a handle.

  Industrial vehicles such as forklifts include a power steering device that controls the driving of the steered wheels in the steering direction according to the turning angle of the steering wheel. The power steering apparatus includes a mechanical type in which the handle and the steering wheel are connected by a mechanical link, and a steer-by-wire type in which the handle and the steering wheel are not mechanically connected.

  The steer-by-wire type power steering device detects a turning angle of a steering wheel with a sensor, and steers a steered wheel with a drive motor in accordance with the turning angle (for example, Patent Literature 1 and Patent Literature 2). This power steering device can turn the steering wheel even if the steering wheel cannot turn due to contact with a curb or the like on the road, so the direction of the steering wheel may not match the direction of the steering wheel. Poor operability.

There is also a power steering device that feeds back a reaction force from a steered wheel to a steering wheel (for example, Patent Document 3). This power steering device detects the steering direction of a steered wheel and feeds back a reaction force from the steered wheel to a handle by a steering reaction force actuator to achieve matching of the angle between the handle and the steered wheel. However, since the structure of the reaction force actuator is not taken into consideration, when an electric motor or brake is adopted, the handle can be operated even when the power is turned off, and the handle is turned when the power is off. When the power is turned on, the direction of the steering wheel and the steered wheel may be greatly deviated.
JP 2004-203075 A JP 2000-351379 A JP 2006-151073 A, paragraph number 0018, FIG.

  Therefore, the problem to be solved by the present invention is to provide a steer-by-wire type power steering device in which the steering angle of the steered wheels is fed back to the steering wheel and the steering wheel cannot be operated when the power is turned off.

The present invention relates to a steer-by-wire power steering device that drives a steered wheel in a steering direction according to a turning angle of a handle.
A handle device coupled to the handle;
A steering drive connected to the steering wheel;
A control unit for controlling the steering device and the steering drive device;
The handle device
An input shaft that rotates according to the turning angle of the handle;
A feedback shaft provided on the same axis as the input shaft;
A worm wheel on the feedback shaft;
A worm coupled to the worm wheel;
A feedback drive that rotates the worm;
A restricting portion for restricting a deviation angle between the input shaft and the feedback shaft within a predetermined range;
A displacement angle sensor for detecting the displacement angle.
The steering drive is
A steering wheel drive unit for driving the steering wheel in the steering direction;
A steering angle sensor for detecting a steering angle of the steered wheels.
The control unit
The steering wheel drive unit is driven based on the deviation angle signal from the deviation angle sensor, the feedback drive unit is driven based on the steering angle signal from the steering angle sensor, and the feedback shaft is rotated following the rotation of the input shaft. Rotate.

  Preferably, an urging portion for urging the deviation angle to the neutral position is provided.

  The control unit controls the rotation angle of the feedback shaft so as to substantially coincide with the steering angle when the turning angle is in a predetermined first range from the straight traveling position toward the steering end, and in a second range outside the first range. At this time, the rotation angle of the feedback shaft is controlled to be different from the steering angle.

  The steer-by-wire type power steering device according to the present invention drives a steered wheel drive unit based on a signal from a deviation angle sensor, and drives a feedback drive unit based on a signal from the steering angle sensor. Therefore, the feedback shaft rotates following the rotation of the input shaft by turning the handle. Furthermore, the restricting portion restricts the relative deviation angle between the input shaft and the feedback shaft to a predetermined angle, so that the input shaft (handle) does not rotate ahead of the feedback shaft (steering wheel) by a predetermined angle or more. Thereby, the steering angle of the steering wheel can be fed back to the steering wheel.

  Furthermore, the feedback shaft is connected to the worm wheel via a worm. The worm is rotated by a feedback drive unit. Since the rotational force from the worm wheel to the worm is not transmitted, the feedback shaft rotates only with the driving force of the feedback drive unit. That is, when the power is turned off, the feedback drive unit stops and the rotation of the feedback shaft is restricted. Further, since the restricting portion restricts the relative deviation angle between the input shaft and the feedback shaft to a predetermined angle, the rotation of the input shaft is restricted and the handle cannot be turned. As a result, the steering wheel does not turn when the power is off, so that the direction of the steering wheel and the steered wheels does not deviate greatly when the power is turned on.

  Hereinafter, a steer-by-wire power steering apparatus according to the present invention will be described with reference to the accompanying drawings.

[overall structure]
FIG. 1 is a side view showing a forklift. In FIG. 1, the part related to the power steering apparatus according to the present invention is indicated by a solid line, and the other part is indicated by a two-dot chain line.
As shown in FIG. 1, the forklift includes a vehicle body 100, a seat 101, a fork 102, and a mast 103. The operator sits on the seat 101 and performs operations such as raising and lowering the fork 102 along the mast 103.

  The forklift includes a handle 5, a front wheel 104, and a steering wheel (rear wheel) 6. An operator seated on the seat 101 turns the steering wheel 5 to rotate the steering wheel 6 in the steering direction (from the straight traveling direction to the left-right direction). The forklift includes a handle device 1 connected to the handle 5, a steering drive device 3 connected to the steering wheel 6, and a control unit 4 that controls the handle device 1 and the steering drive device 3.

[Steering drive unit]
The steering drive device 3 includes a steering wheel drive unit 30 including an electric cylinder and an EPS motor. The steering drive device 3 is connected to the steering wheel 6 and includes a steering rotation shaft 32 that rotates in the steering direction about the shaft center. The steering wheel drive unit 30 transmits a driving force to the steering rotation shaft 32 via a speed reduction mechanism (interlocking mechanism) 33 including a gear device, a link mechanism, and the like.

  As will be described in detail later, the control unit 4 drives the steered wheel drive unit 30 in accordance with a signal from the handle device 1 based on the turning of the handle 5, and steers via the speed reduction mechanism 33 and the steering rotation shaft 32. The wheel 6 is driven in the steering direction. The steering drive device 3 includes a steering angle sensor 31 for detecting a steering angle θ4 in the steering direction of the steering wheel 6. The control unit 4 drives the handle device 1 in accordance with a signal from the steering angle sensor 31 based on the steering angle θ4.

[Handle device]
FIG. 2 is a diagram illustrating the handle device. 2A is a side sectional view, and FIG. 2B is a sectional view taken along the line II of FIG.

  As shown in FIG. 2, the handle device 1 includes a housing part 19 fixed to the vehicle body 100. The handle device 1 includes an input shaft 10 connected to the handle 5. The input shaft 10 is configured to be rotatable around a central shaft 110 extending in the vertical direction via a bearing 10 a provided in the housing portion 19. In synchronization with the turning angle of the handle 5, the input shaft 10 rotates around the central axis 110.

  The handle device 1 includes a feedback shaft 11. The feedback shaft 11 is configured to be rotatable around the central shaft 110 via a bearing 11 a provided in the housing portion 19. Further, the feedback shaft 11 rotates around the central axis 110, which is the same axis as the input shaft 10, independently of the input shaft 10.

  The handle device 1 includes a deviation angle sensor 12. The deviation angle sensor 12 detects a relative deviation angle Δθ (θ1−θ2) between the rotation angle θ1 of the input shaft 10 and the rotation angle θ2 of the feedback shaft 11. The deviation angle sensor 12 includes a pickup gear 120. The pickup gear 120 is configured to be movable in the direction of the central axis 110. The pickup gear 120 has a helical gear 121 and a spur gear 122.

  The input shaft 10 has a helical gear 123 and meshes with a helical gear 121 of a pickup gear. Further, the feedback shaft 11 has a spur gear 125 and meshes with a spur gear 122 of a pickup gear. As a result, the pickup gear 120 moves in the direction of the central axis 110 (vertical direction) in proportion to the deviation angle Δθ between the input shaft 10 and the feedback shaft 11.

  The deviation angle sensor 12 includes a potentiometer 126. When the potentiometer 126 detects the vertical position of the pickup gear 120, the deviation angle sensor 12 detects the deviation angle Δθ between the input shaft 10 and the feedback shaft 11.

  The deviation angle sensor 12 is not limited to the above configuration, and includes, for example, a rotation sensor that detects the rotation angle θ1 of the input shaft and a rotation sensor that detects the rotation angle θ2 of the feedback shaft, and these rotation angles θ1. , Θ2 may be configured by a device for calculating the difference Δθ.

  The handle device 1 includes a worm portion 2. The worm unit 2 includes a worm wheel 21. The worm wheel 21 is provided on the feedback shaft 11. The worm unit 2 includes a worm 20. The worm 20 is configured to be rotatable via a bearing 20 a provided in the housing portion 19. The handle device 1 includes a feedback drive unit 13. The feedback drive unit 13 rotationally drives the worm 20.

  The worm part 2 rotates the worm wheel 21 by the rotation of the worm 20. That is, the worm portion 2 is configured so that the worm wheel 21 does not rotate unless the worm 20 rotates. Since the worm 20 is configured to be rotationally driven by the feedback drive unit 13, the feedback shaft 11 rotates according to the output of the feedback drive unit 13.

  The handle device 1 includes a feedback shaft angle sensor 14. The feedback shaft angle sensor 14 detects the rotation angle θ2 of the feedback shaft 11.

[Regulation Department]
FIG. 3 is a cross-sectional view taken along the line II-II in FIG.
The handle device 1 includes a restricting portion 15 for restricting the deviation angle Δθ between the input shaft 10 and the feedback shaft 11 to a predetermined angle range (−θ3 to + θ3) (FIG. 2). The restriction unit 15 is provided on the input shaft 10 and the feedback shaft 11.

  Therefore, when the rotation of the feedback shaft 11 is stopped, the restricting portion 15 can restrict the rotation of the input shaft 10 within a predetermined angle range (−θ3 to + θ3), so that the rotation of the input shaft 10 is substantially stopped. The turning of the handle 5 can be disabled.

  As shown in FIG. 3, the restricting portion 15 includes a center pin 150 and a stopper pin 151. The center pin 150 is provided at the center of the input shaft 10 (center shaft 110). The stopper pin 151 is provided opposite to both sides of the input shaft 10. The restricting portion 15 includes a biasing portion 152 made of a pair of leaf springs on both sides of the center pin 150.

  The restricting portion 15 includes a first contact portion 153 and a second contact portion 154. The first contact portion 153 is provided on the input shaft 10. The second contact portion 154 is provided on the feedback shaft 11. The first contact portion 153 and the second contact portion 154 are arc-shaped and provided in parallel. In this example, four first contact portions 153 and second contact portions 154 are provided around the center pin 150 at intervals. A stopper pin 151 and a biasing portion 152 are disposed between the first contact portion 153 and the second contact portion 154, respectively.

  As described above, the input shaft 10 is provided with the center pin 150, the stopper pin 151, and the first contact portion 153. The feedback shaft 11 is provided with a second contact portion 154. Accordingly, when the input shaft 10 is rotated, the stopper pin 151 and the first abutting portion 153 rotate around the center pin 150.

  FIG. 3B shows a case where the deviation angle Δθ between the input shaft and the feedback shaft is 0 (neutral position). The neutral position is a position where the handle 5 is not turned left or right from a predetermined position. In the neutral position, the stopper pin 151 does not contact the second contact portion 154. Then, the urging portion 152 does not urge the first contact portion 153 and the second contact portion 154.

  FIG. 3A shows a case where the deviation angle Δθ between the input shaft and the feedback shaft is −θ3 (counterclockwise). When the handle 5 (input shaft 10) is rotated from the center position to the left (counterclockwise), the stopper pin 151 and the first contact portion 153 move the center pin 150 relative to the second contact portion 154. Rotate left to center.

  Therefore, the input shaft 10 is rotatable until the stopper pin 151 contacts the second contact portion 154 (until the deviation angle Δθ becomes −θ3). When the input shaft 10 rotates, the urging portion 152 is in a state where one side (becomes the fixed end side) is in contact with the second contact portion 154 and the other side (becomes the free end side) is the first. The urging force is stored by being pushed by the contact portion 153. Therefore, when the operator stops the turning of the handle 5, it returns to the neutral position (FIG. 3B) by the urging force to return to the urging portion 152.

  FIG. 3C shows a case where the deviation angle Δθ between the input shaft and the feedback shaft is + θ3 (clockwise in the figure). When the handle 5 (input shaft 10) is rotated from the center position to the right (clockwise in the figure), the input shaft 10 is moved until the stopper pin 151 hits the second contact portion 154 (shift angle Δθ) as in the case of the counterclockwise rotation. (Until + θ3). Further, when the operator stops turning the handle 5, the operator returns to the neutral position (FIG. 3B) by the urging force to return the urging unit 152 to the original position.

  In addition, the control part 15 can be comprised not only with the said structure but well-known techniques, such as a combination of a rail and a pin. Further, the urging portion 152 is not limited to a leaf spring but can be constituted by a torsion coil spring or the like.

[Power steering device]
FIG. 4 is a block diagram showing the power steering apparatus.
As shown in FIG. 4, the power steering device includes a handle device 1, a control unit 4, and a steering drive device 3. The handle device 1 and the steering drive device 3 are configured as described above. The control unit 4 includes a steering controller 40 and a feedback controller 41.

  When the operator turns the handle 5, the input shaft 10 is rotated by the rotation angle θ1 accordingly. The deviation angle sensor 12 detects a deviation angle Δθ between the rotation angle θ1 of the input shaft and the rotation angle θ2 of the feedback shaft. The deviation angle sensor 12 outputs a signal of the deviation angle Δθ to the steering controller 40 (FIG. 2A).

  The steering controller 40 drives the steering wheel drive unit 30 based on the deviation angle Δθ. When the deviation angle Δθ is −Δθ (counterclockwise), the steering controller 40 drives the steering wheel drive unit 30 so that the steering rotation shaft 32 rotates clockwise, and when the deviation angle Δθ is + Δθ (clockwise). The steering wheel drive unit 30 is driven so that the steering rotation shaft 32 rotates counterclockwise.

  In response to the left and right rotation of the steering rotation shaft 32, the steering wheel 6 turns in the steering direction. The steering angle sensor 31 detects the steering angle (rotation angle) θ4 of the steering wheel 6 (steering rotation shaft 32). The steering angle sensor 31 outputs a signal of the steering angle θ4 to the feedback controller 41.

  The feedback controller 41 inputs a signal of the steering angle θ4 of the steered wheel from the steering angle sensor 31. The feedback controller 41 controls the feedback drive unit 13 so that the feedback shaft 11 rotates by the rotation angle θ2 based on the steering angle θ4 and a predetermined function f (θ) set in advance.

  Further, the feedback controller 41 inputs a signal of the rotation angle θ2 of the feedback shaft from the feedback shaft angle sensor 14. As a result, the feedback controller 4 determines whether the feedback shaft 11 is rotated at the target rotation angle θ2 (based on the predetermined function f (θ)), and controls to match if there is a deviation. .

  As described above, the feedback shaft 11 rotates so as to follow the rotation of the input shaft 10. Therefore, even if the regulating portion 15 regulates the deviation angle Δθ between the input shaft 10 and the feedback shaft 11 within a predetermined angle range, the steering is performed. The handle 5 can be turned until the wheel 6 reaches the left and right steering ends.

  Further, the feedback shaft 11 is connected to a worm wheel 21 via a worm 20. Since the rotation is not transmitted from the worm wheel 21 to the worm 20, the feedback shaft 11 rotates only by driving the feedback drive unit 13 (FIG. 2).

  The forklift is provided with a power source 7 such as a battery (FIG. 1), and drives each drive unit 13, 30 and the like by the power of the power source 7. Therefore, when the power is turned off, the feedback drive unit 13 stops and the rotation of the feedback shaft 11 is restricted. Then, since the restricting portion 15 restricts the relative deviation angle Δθ between the input shaft and the feedback shaft to a predetermined angle, the rotation of the input shaft 10 is restricted and the handle 5 cannot be turned. Thereby, when the power is turned on, the directions of the handle 5 and the steered wheels 6 do not deviate greatly.

[Predetermined function f (θ)]
FIG. 5 is a graph for explaining the predetermined function f (θ). As described above, the feedback controller 41 sets the rotation angle θ2 of the feedback shaft 11 based on the input steering angle θ4 and the predetermined function f (θ) set in advance.

  The steering angle θ4 is from 0 (straight forward direction) to + θ42 (right steering end) clockwise and from 0 (straight forward direction) to −θ42 (left steering end) counterclockwise. The first predetermined function f1 (θ) is a polygonal line function, and is a linear fold function broken at a point (0 <| θ41 | <| θ42 |) where the steering angle θ4 becomes + θ41 and −θ41.

  When the steering angle θ4 is in the range of −θ41 to + θ41 (first range S1), the proportionality constant is a linear function of 1.0, and the rotation angle θ2 matches the turning angle θ4 (| θ41 | = | θ21 | ). Further, in the range where the steering angle θ4 is from −θ42 to −θ41 and the range from + θ41 to + θ42 (second range S2), the proportionality constant is a linear function smaller than 1.0, and the rotation angle θ2 is the turning angle θ4. (| Θ42 |> | θ22 |).

  Therefore, in the first range S1, the rotation angle θ2 coincides with the steering angle θ4, so that the operator can obtain steering sensitivity that is synchronized with the turning of the handle 5 in the range where the vehicle turns slightly from the straight direction. In addition, in the second range S2, the rotation angle θ2 is smaller than the steering angle θ4, so that the operator can obtain steering sensitivity that is sensitive to turning of the handle 5 in a range in which the vehicle turns significantly from the straight direction. Therefore, the operator can steer the steered wheel with a small number of steering wheel rotations.

The second predetermined function f2 (θ) is a curve function obtained by continuously changing the first predetermined function f1 (θ) into a curved shape, and has similar characteristics (two-dot chain line in the figure).
Further, in the second range S2, the steering angle can be made dull by making the rotation angle θ2 larger than the steering angle θ4 (| θ42 | <| θ22 |).

It is a side view which shows a forklift. It is a figure which shows a handle apparatus. It is sectional drawing which shows a control part. It is a block diagram which shows a power steering apparatus. It is a graph for demonstrating the predetermined function f ((theta)).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Handle apparatus 10 Input shaft 12 Deviation angle sensor 11 Feedback shaft 13 Feedback drive part 14 Feedback shaft angle sensor 15 Control part 110 Central axis 2 Worm part 20 Worm 21 Worm wheel 3 Steering drive apparatus 30 Steering wheel drive part 31 Steering angle sensor 4 Control unit 5 Steering wheel 40 Steering controller 41 Feedback controller 6 Steering wheel f (θ) Predetermined function θ1 Input shaft rotation angle θ2 Feedback shaft rotation angle Δθ Deviation angle between input shaft and feedback shaft

Claims (3)

In the steer-by-wire type power steering device that drives the steered wheels in the steering direction according to the turning angle of the steering wheel,
A handle device coupled to the handle;
A steering drive connected to the steering wheel;
A control unit for controlling the handle device and the steering drive device;
The handle device is
An input shaft that rotates according to the turning angle of the handle;
A feedback shaft provided on the same shaft as the input shaft;
A worm wheel provided on the feedback shaft;
A worm coupled to the worm wheel;
A feedback drive for rotating the worm;
A restricting portion for restricting a deviation angle between the input shaft and the feedback shaft within a predetermined range;
A deviation angle sensor for detecting the deviation angle;
The steering drive device
A steering wheel drive unit for driving the steering wheel in a steering direction;
A steering angle sensor for detecting a steering angle of the steering wheel,
The controller is
The steering wheel driving unit is driven based on a deviation angle signal from the deviation angle sensor, and the feedback driving unit is driven based on a steering angle signal from the steering angle sensor to follow the rotation of the input shaft. And rotating the feedback shaft.   The power steering apparatus according to claim 1, further comprising an urging portion for urging the deviation angle to a neutral position.   The control unit controls the rotation angle of the feedback shaft so that the rotation angle of the feedback shaft substantially coincides with the steering angle when the turning angle is in a predetermined first range from the straight traveling position toward the steering end, and deviates from the first range. 3. The power steering apparatus according to claim 1, wherein in the second range, the rotation angle of the feedback shaft is controlled to be different from the steering angle. 4.

Images