JP2004034751A - Steering gear for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering gear for a vehicle for making a steering means and a steering wheel have the same phase when changing a mode from an automatic mode enabling an automatic maneuvering corresponding to an ITS (Intelligent Transport Systems) in a steer-by-wire type (SBW type) or transmission ratio variable type steering gear, etc. <P>SOLUTION: This SBW type or transmission ratio variable type steering gear, etc. is provided with a steering control part provided with a means for controlling steering by a manual mode or an automatic mode, a mode change receiving part to receive an instruction for changing the mode, a steering actuator capable of changing a steering angle of the steering means, and a steering angle sensor capable of detecting a steering angle θ20 of the steering wheel. The steering means is rotated and driven to make a steering angle θ1 of the steering means correspond to a corresponding steering angle θ2 corresponding to the steering angle θ20 of the steering wheel. After the corresponding, the mode is changed to the manual mode. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle steering device that changes the direction of a steered wheel of a vehicle according to a steering amount of a steering device such as a steering wheel operated by a driver.
[0002]
[Prior art]
There are various types of vehicular steering devices. Recently, steer-by-wire type steering devices and variable transmission ratio type steering devices have attracted attention.
[0003]
The steer-by-wire steering device arranges steering means inside the vehicle interior and a steering mechanism outside the vehicle interior without mechanical connection, and further includes a steering actuator attached to a part of the steering mechanism. The steering actuator is configured to operate based on a detection result of an operation direction and an operation amount of the steering means, and to apply a driving force to a steering mechanism to perform steering according to the operation of the steering means. is there.
[0004]
Such a steer-by-wire type steering device can freely change the correspondence between the operation amount of the steering means and the operation amount of the steering mechanism due to the operation of the steering actuator without any mechanical restrictions. In addition, there is an advantage that it is possible to flexibly cope with control for changing the steering characteristics according to the traveling state, such as the vehicle speed and the presence or absence of acceleration / deceleration.
[0005]
On the other hand, a variable transmission ratio type steering device is provided with a transmission device capable of changing the rotation transmission ratio between an input shaft that rotates in accordance with an operation of a steering means and an output shaft that rotates in conjunction with the operation of a steering mechanism. And the rotation transmission ratio is variably controlled in accordance with the running state, whereby steering characteristics adapted to the running state are obtained. The transmission is a planetary gear mechanism and includes a sun gear connected to an input shaft, a planetary gear held on a carrier connected to an output shaft and meshing with the sun gear, and a ring gear that is rotationally driven and controlled by a motor and meshes with the planetary gear. .
[0006]
A vehicle equipped with the above-described steer-by-wire or variable transmission ratio type steering device is premised on that the driver operates the steering means or the like to steer the vehicle. Further, recently, as one of intelligent transport systems (ITS), a driving support road system (Automated Cruises-Assist Highway System: AHS) has been researched and developed. Such AHS is intended for vehicles equipped with the above-mentioned steer-by-wire type or variable transmission ratio type steering device, to provide a route guidance infrastructure and an information collection infrastructure on the road side, and to establish a connection between the road side infrastructure and the vehicle. And the like, thereby realizing automatic traveling of the vehicle.
[0007]
[Problems to be solved by the invention]
In the above-mentioned AHS, it is difficult to imagine that all roads support the AHS because the route guidance infrastructure and the like are also required on the road side. In the steering device mounted on the vehicle, the automatic mode corresponding to the AHS is not available. And a manual mode in which the driver operates the vehicle.
[0008]
In a steer-by-wire type steering apparatus, when a vehicle travels in an automatic mode, usually, the steering means is stationary, and only the steered wheels steer left and right to steer the vehicle. When the mode is changed to the manual mode in this state, the phases of the steering means and the steered wheels do not match because the steering means and the steered wheels are not linked. Therefore, when the steering means is operated in a state where the phases of the steering means and the steered wheels are shifted, there is a problem that the driver feels a sense of discomfort.
[0009]
Further, in the variable transmission ratio steering device, when the driver has released his / her hand from the steering means in the automatic mode, in order to make the rotation angle of the output shaft coincide with the target rotation angle corresponding to the rotation angle of the input shaft. Even when the motor is driven and controlled, the rotation of the output shaft is transmitted to the input shaft via the planetary gear mechanism, and the target rotation angle fluctuates due to the rotation of the input shaft. May be out of phase. Also, when the transmission ratio is changed during the operation of the steering means, and the mode is changed from the manual mode to the automatic mode before returning to the neutral position, when the automatic steering is performed with the transmission ratio fixed, the steering is performed. The neutral position of the wheel and the steering means does not match. When the mode is changed to the manual mode in this state, the phases of the input shaft and the output shaft are shifted. When the steering means is operated in a state where the phases of the steering means and the steered wheels are out of phase, there is a problem that the driver feels a sense of discomfort in the steering similarly to the steer-by-wire steering apparatus.
[0010]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a vehicle steering device that adjusts the phases of a steering unit and a steered wheel when changing from an automatic mode to a manual mode.
[0011]
[Means for Solving the Problems]
A vehicle steering system according to a first aspect of the present invention includes a steering mechanism that changes the direction of a steered wheel, a steering actuator that applies a driving force to the steering mechanism, and is not mechanically connected to the steering mechanism. A steering unit connected to an upper part of a rotating shaft, a steering angle sensor for detecting a steering angle of the steering unit, a steering angle sensor for detecting a steering angle of the steered wheel, the steering angle sensor and the steering A steering control unit that performs drive control of the steering actuator in accordance with the detection result of the angle sensor, wherein the steering control unit performs drive control of the steering actuator in accordance with steering of the steering means. Means for controlling steering in a manual mode for performing steering or in an automatic mode for performing drive control of the steering actuator in response to an external guidance signal, and accepting an instruction to change between the manual mode and the automatic mode A mode change receiving unit, a steering actuator that applies a rotational force to the rotating shaft to change a steering angle of the steering unit, and whether the mode change receiving unit receives an instruction to change from the automatic mode to the manual mode. Reception judging means for judging whether or not the steering angle of the steering means and the rotation of the steered wheels are determined from the detection results of the steering angle sensor and the steering angle sensor when the reception judgment means judges that the instruction has been received. The same determining means for determining whether or not the corresponding steering angle of the steering means corresponding to the steering angle is the same; and, when the same determining means determines that the steering angle is not the same, the steering angle of the steering means and the steering wheel Control means for controlling the operation of the steering actuator in order to make a corresponding steering angle of the steering means correspond to the turning angle of the steering wheel.
[0012]
In the first invention, when changing from the automatic mode to the manual mode with the steer-by-wire steering device, the respective phases of the steering means and the steered wheels are detected, and when the phases of the steering means and the steered wheels are different, The steering means is rotationally driven to match the phase of the steered wheels. Accordingly, when changing to the manual mode, there is no phase shift between the steering means and the steered wheels, and there is no uncomfortable feeling in operating the steering means even after changing to the manual mode.
[0013]
When the same determination means determines that they are the same, there is no phase shift between the steering means and the steered wheels. Therefore, the mode is changed from the automatic mode to the manual mode without driving control of the steering actuator.
[0014]
A steering apparatus for a vehicle according to a second aspect of the present invention includes a steering mechanism that changes the direction of a steered wheel, a steering actuator that applies a driving force to the steering mechanism, and is not mechanically connected to the steering mechanism. A steering unit connected to an upper part of a rotating shaft, a steering angle sensor for detecting a steering angle of the steered wheel, and a steering actuator in accordance with the steering of the steering unit and a detection result of the steering angle sensor. A steering control unit for performing drive control of the vehicle, wherein the steering control unit performs a manual mode for performing drive control of the steering actuator in accordance with the steering of the steering unit, or sets the steering unit to a neutral position. Means for controlling steering in an automatic mode for controlling the driving of the steering actuator in response to an external guidance signal, and a mode for receiving an instruction to change between the manual mode and the automatic mode. Mode change receiving unit, a reception determining unit that determines whether the mode change receiving unit has received an instruction to change from the automatic mode to the manual mode, and when the reception determining unit determines that the instruction has been received, Neutral determining means for determining whether the steering angle detected by the steering angle sensor is at a neutral position, and changing from the automatic mode to the manual mode when the neutral determining means determines that the neutral position is at the neutral position. And changing means for performing the operation.
[0015]
In the second invention, when changing from the automatic mode to the manual mode with the steer-by-wire steering device, the steered angle of the steered wheels is detected, and it is determined whether or not the steered angle of the steered wheels is at the neutral position. . It is possible to change to the manual mode only when the steered wheels are at the neutral position, and there is no need to rotate the steering means to adjust the phase as in the first invention. There is no phase shift between the steering means and the steered wheels, so that the mode can be safely changed to the manual mode.
[0016]
A steering device for a vehicle according to a third aspect of the present invention is a steering device connected to an upper portion of an input shaft, a steering mechanism for changing a direction of a steered wheel, an output shaft connected to the steering mechanism, and the input shaft. A rotation transmission ratio variable means interposed between the output shaft and the output shaft, a steering actuator for applying a driving force to the steering mechanism, a steering angle sensor for detecting a steering angle of the steering means, and the steering angle sensor A steering control unit that controls the change of the rotation transmission ratio of the rotation transmission ratio variable unit in accordance with the detection result of the steering control unit and controls the drive of the steering actuator in accordance with the steering of the steering unit. The steering control unit controls the steering in a manual mode for controlling the driving of the steering actuator in accordance with the steering of the steering means or in an automatic mode for controlling the driving of the steering actuator in response to an external guidance signal. Means, a mode change receiving unit that receives a change instruction between the manual mode and the automatic mode, a turning angle sensor that detects a turning angle of the steered wheels, and a turning force applied to the input shaft. A steering actuator for changing a steering angle of the steering means; a reception determining means for determining whether the mode change receiving section has received an instruction to change from the automatic mode to the manual mode; and When it is determined that the steering angle is received, the steering angle of the steering unit and the corresponding steering angle of the steering unit corresponding to the steering angle of the steered wheels are the same based on the detection results of the steering angle sensor and the steering angle sensor. The same determining means for determining whether or not there is, and when the same determining means determines that there is no, a steering angle of the steering means and a corresponding steering angle of the steering means corresponding to a turning angle of the steered wheel. Correspondence And a controlling means for controlling the operation of the steering actuator in order.
[0017]
In the third aspect, when changing from the automatic mode to the manual mode with the variable transmission ratio type steering device, the respective phases of the steering means and the steered wheels are detected, and when the phases of the steering means and the steered wheels are different, The steering means is rotationally driven to match the phase of the steered wheels. Accordingly, when changing to the manual mode, there is no phase shift between the steering means and the steered wheels, and there is no uncomfortable feeling in operating the steering means even after changing to the manual mode.
[0018]
Also in the vehicle steering system according to the third aspect, when the same determination means determines that they are the same, since there is no phase shift between the steering means and the steered wheels, the drive control of the steering actuator is performed. Change from automatic mode to manual mode without incident.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments.
Embodiment 1
FIG. 1 is a schematic block diagram illustrating a mechanical configuration of a vehicle steering system according to a first embodiment of the present invention.
[0020]
In the drawing, reference numeral 1 denotes a steering mechanism, and the steering mechanism 1 is for steering a pair of steering wheels 10, 10 disposed on the left and right of a front part of a vehicle body (not shown). A steering means (steering wheel) 2 that is rotated for steering is connected to an upper end of the column shaft 20 and is disposed at an appropriate position without being mechanically connected to the steering mechanism 1. In order to realize steering according to the operation of the steering means 2, the steering mechanism 1 is provided with a steering motor M1, which is a steering actuator, and applies a reaction force to the steering means 2 to perform steering of the steering means 2. A reaction motor M2, which is a steering actuator capable of changing the angle, is attached to a column housing H3 that supports the column shaft 20, and a steering control unit 3 that controls the driving of the steering motor M1 and the reaction motor M2 is appropriately operated. It is located at the location. Between the steering mechanism 1 and the column shaft 20, there is provided a connecting means 4 capable of obtaining a driving connection state when the steering control unit 3 or the like fails.
[0021]
The steering mechanism 1 is a rack and pinion type steering mechanism, and includes a rack shaft 11 that is disposed in the left and right direction at the front of a vehicle body (not shown) and that can move in the longitudinal direction. Tie rods 13, 13 are connected to both ends of the rack shaft 11, and the tie rods 13, 13 are connected to knuckle arms 12, 12 of the steered wheels 10, 10, respectively.
[0022]
The steering motor M1 is provided in the middle of one end side of a cylindrical rack housing H1 that supports the rack shaft 11 movably in the longitudinal direction, and includes a motion conversion mechanism such as a ball screw mechanism inside the rack housing H1. It is connected to the middle of the rack shaft 11 through the middle. The steering motor M1 is rotationally driven in accordance with a drive signal given from the steering control unit 3 to a drive circuit (not shown) for the steering motor M1.
[0023]
A steering angle sensor 17 is provided at a connection between the rack shaft 11 and one of the tie rods 13. The steering angle sensor 17 detects the displacement of the connection to rotate the steered wheels 10, 10. This is to detect the steering angle. The detection result of the turning angle sensor 17 is given to the steering control unit 3. One tie rod 13 is provided with a tie rod axial force sensor 18 for detecting an axial force acting in the axial direction, and the detection result indicates a steering reaction force actually applied to the steering mechanism 1 with the steering. The signal is given to the steering control unit 3 as a signal.
[0024]
A pinion housing H2 intersecting with the rack housing H1 is continuously provided in the middle of the other end portion side of the rack housing H1, and a pinion shaft 14 is rotatably supported around an axis inside the pinion housing H2. are doing. A pinion (not shown) is formed integrally with the lower half of the pinion shaft 14, and the pinion meshes with rack teeth (not shown) formed on the rack shaft 11 at the intersection of the rack housing H1 and the pinion housing H2. .
[0025]
The transmission shaft 16 is connected to the upper end of the pinion shaft 14 projecting above the pinion housing H2 via a universal joint 15a, an intermediate shaft 15b and a universal joint 15c. The transmission shaft 16 is rotatably supported around the axis, and extends upward toward the position where the steering means 2 is disposed.
[0026]
The steering means 2 is supported at an appropriate position on a vehicle body (not shown) via a column shaft 20 and a column housing H3 that rotatably supports the column shaft 20 around the axis. A reaction force motor M2 that is rotationally driven to apply a steering reaction force to the steering means 2 is provided at an intermediate portion of the column housing H3. The output shaft of the reaction motor M2 extends inside the column housing H3, and is connected to an intermediate portion of the column shaft 20 via a speed reduction mechanism such as a worm gear mechanism. The reaction motor M2 is driven according to a drive signal given from the steering control unit 3 to a drive circuit (not shown) for the reaction motor M2.
[0027]
The steering angle of the rotating steering means 2 is detected by a steering angle sensor 21 attached to a middle part of the column housing H3, and the detection result is given to the steering control unit 3. The steering angle of the steering means 2 is “+” on the right rotation direction side from the neutral position, and “−” on the left rotation direction side from the neutral position.
[0028]
The lower end of the column shaft 20 projects below the column housing H3 and is opposed to the upper end of the transmission shaft 16 extended from the steering mechanism 1, and a coupling means 4 such as an electromagnetic clutch or a friction clutch is provided at the opposed portion. It is interposed. The connecting means 4 is operated by a connecting signal given from the steering control unit 3 and operates to connect the transmission shaft 16 and the column shaft 20. The steering means 2 and the steering mechanism 1 are connected to the column shaft 20, the connecting means 4, It is mechanically connected via a transmission shaft 16, a universal joint 15c, an intermediate shaft 15b, a universal joint 15a, a pinion shaft 14, and a pinion (not shown).
[0029]
The steering control unit 3 includes a CPU, a ROM, and a RAM, and controls the driving of the steering motor M1 and the like in accordance with a detection result detected by the steering angle sensor 21 when the driver operates the steering means 2 to control the steering of the vehicle. The "manual mode" to be performed and the "auto mode" in which the steering motor M1 and the like are driven and controlled by a guidance signal from the road side and the vehicle can be steered without the driver of the vehicle operating the steering means 2. Steering is controlled by two modes. The steering control unit 3 calculates a corresponding steering angle of the steering means 2 corresponding to the turning angle of the steered wheels 10 provided by the turning angle sensor 17.
[0030]
The steering control unit 3 is provided at an appropriate position of the vehicle and detects a detection result of the traveling state sensor 22 for detecting vehicle speed, acceleration / deceleration, yaw rate, and the like, and a guidance signal for automatically steering the vehicle. And a mode change instruction signal from the mode change accepting unit 23 that accepts an instruction to change between the manual mode and the automatic mode.
[0031]
With the above configuration, the vehicle steering system according to the present invention realizes the steering of the vehicle according to the operation direction and the operation amount of the steering unit 2 in the manual mode, similarly to the conventional steer-by-wire steering system. In the automatic mode, the steering control unit 3 controls the driving of the steering motor M1 and the like based on the guidance signal detected by the guidance signal detection unit 24, thereby realizing automatic steering of the vehicle. At this time, since the occupant of the vehicle does not need to operate the steering device 2, the steering device 2 is usually stopped at the neutral position or the rotation position when the mode is changed to the automatic mode.
[0032]
Next, a case where the mode is changed from the automatic mode to the manual mode will be described with reference to a flowchart of FIG. 2 showing a process related to a mode change control performed by the steering control unit 3 in the first embodiment.
[0033]
First, the steering control unit 3 determines whether or not a change instruction signal for changing from the automatic mode to the manual mode is given from the mode change receiving unit 23 (S1). When the change instruction signal for changing to the manual mode is not given (S1, NO), the steering control unit 3 repeatedly determines until the change instruction signal is given, and when it is given (S1, YES), the steering control unit 3 Reads the steering angle θ1 of the steering means 2 (S2).
[0034]
Next, the steering control unit 3 reads the turning angle θ20 of the steered wheels 10, 10 (S3), and calculates a corresponding steering angle θ2 corresponding to the read turning angle θ20 (S4).
[0035]
Next, the steering control unit 3 determines whether or not the steering angle θ1 of the steering unit 2 is the same as the corresponding steering angle θ2 of the steering unit 2 corresponding to the turning angle θ20 of the steered wheels 10, 10. (S5). When the steering angle θ1 is equal to the corresponding steering angle θ2 (S5, YES), the steering control unit 3 changes the mode from the automatic mode to the manual mode (S6), and ends the processing.
[0036]
If the steering angle θ1 is not the same as the corresponding steering angle θ2 in S5 (S5, NO), the steering controller 3 calculates an angle difference A obtained by subtracting the corresponding steering angle θ2 from the steering angle θ1 (S7). The steering control unit 3 determines whether or not the angle difference A is “negative” (S8). If the angle difference A is “negative” (S8, YES), the steering control unit 3 controls the steering means 2 by the reaction motor M2. A right rotation is made by | A | angle (S9). If the angle difference A is "positive" in S8 (S8, NO), the steering control unit 3 rotates the steering means 2 counterclockwise by the angle | A | using the reaction force motor M2 (S10). After S9 or S10, the steering control unit 3 changes from the automatic mode to the manual mode (S6), and ends the processing.
[0037]
As described above, when the occupant of the vehicle operates the mode change receiving unit 23 to change from the automatic mode to the manual mode, the steering control unit 3 controls the steering unit 2 and the steering unit 2 as described in the above-described flowchart. If the phases of the directional wheels 10, 10 are different, the steering means 2 is rotated to match the phases of the steered wheels 10, 10, and therefore, when changing from the automatic mode to the manual mode, the steering means 2 and the steered wheels 10, The phases of 10 do not shift.
[0038]
In addition, by implementing the steering device of the steer-by-wire type, the reaction motor M2 can be diverted to the steering actuator for driving the steering means 2, and the cost increase is relatively small compared to the conventional vehicle steering device. The vehicle steering device according to the present invention can be realized.
[0039]
In the first embodiment, the steering motor M1 for applying a driving force to the steering mechanism 1 is attached to the rack housing H1. However, the arrangement position of the steering motor M1 is not limited to the rack housing H1, but may be other positions, for example, The transmission shaft 16 is provided with a reduction gear mechanism, and the rotation of the steering motor M1 is transmitted to the transmission shaft 16 via the reduction gear mechanism, and from the transmission shaft 16, a universal joint 15c, an intermediate shaft 15b, a universal joint 15a, a pinion shaft 14, The steering mechanism 1 may be provided with a driving force via a pinion (not shown).
[0040]
Embodiment 2
Hereinafter, a second embodiment of the vehicle steering system according to the present invention will be described. The same parts as those of the vehicle steering system according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. The different parts will be described below.
[0041]
In the first embodiment, when the steering mode is changed from the automatic mode to the manual mode, if the phases of the steering unit 2 and the steered wheels 10 are different, the reaction motor M2 is controlled by the steering control unit 3 to control the steering unit 2. Was rotated to adjust the phases of the steering means 2 and the steered wheels 10, 10. In the second embodiment, when changing from the automatic mode to the manual mode, the reaction force motor M2 and the steering control unit 3 operate the reaction force motor M2 even if the phases of the steering means 2 and the steered wheels 10, 10 are different. The configuration is such that the steering means 2 is not rotated without driving and controlling the M2.
[0042]
During the automatic mode, the steering means 2 can be set to the neutral position. For example, even if the mode is changed to the automatic mode when the steering means 2 is not at the neutral position, and the steering means 2 stands still at the non-neutral position, the driver can rotate the steering means 2 to the neutral position.
[0043]
Further, the second embodiment includes a display unit 30. The display unit 30 is disposed at an appropriate position where the driver can visually recognize the display unit 30 and displays a message indicating that the change cannot be made between the manual mode and the automatic mode. The display indicating that the change is impossible is performed by an instruction signal from the steering control unit 3.
[0044]
With the above configuration, the vehicle steering system according to the second embodiment realizes the same vehicle steering in the manual mode and the automatic mode as the vehicle steering system according to the first embodiment.
[0045]
Next, a case where the mode is changed from the automatic mode to the manual mode will be described with reference to a flowchart of FIG. 3 illustrating a process related to a mode change control performed by the steering control unit 3 according to the second embodiment.
[0046]
First, the steering control unit 3 determines whether or not a change instruction signal for changing from the automatic mode to the manual mode is given from the mode change receiving unit 23 (S21). When the change instruction signal for changing to the manual mode is not given (S21, NO), the steering control unit 3 repeatedly determines until the change instruction signal is given, and when it is given (S21, YES), the steering control unit 3 Reads the steered angle θ20 of the steered wheels 10, 10 (S22).
[0047]
Next, the steering control unit 3 determines whether or not the turning angle θ20 is “0” (S23), and when the turning angle θ20 is not “0” (S23, NO), the steering control unit 3 An instruction signal for indicating that mode change is not possible is given to the display unit 30 (S25), and the process ends. When the turning angle θ20 is “0” (S23, YES), the steering control unit 3 changes the mode from the automatic mode to the manual mode (S24), and ends the processing.
[0048]
As described above, when the occupant of the vehicle operates the mode change receiving unit 23 in order to change from the automatic mode to the manual mode, the steering control unit 3 controls the steering wheels 10, The automatic mode is changed to the manual mode only when the vehicle 10 is in the neutral position, that is, only when the vehicle is traveling straight. Therefore, the phase of the steering means 2 and the steered wheels 10, 10 does not shift, and the mode can be safely changed to the manual mode with a simpler configuration and control.
[0049]
In the automatic mode, the driver can rotate the steering means 2 to set the neutral position. However, for example, when changing from the manual mode to the automatic mode, the steering means 2 is rotated by the reaction motor M2. A configuration may be employed in which the steering unit 2 is held at the neutral position during the automatic mode by providing a holding unit that is driven to the neutral position and holds the steering unit 2.
[0050]
Embodiment 3
Hereinafter, a third embodiment of the vehicle steering system according to the present invention will be described. FIG. 4 is a schematic block diagram illustrating a mechanical configuration of a vehicle steering system according to a third embodiment of the present invention. 1 are denoted by the same reference numerals, description thereof will be omitted, and description of different portions will be described below.
[0051]
In FIG. 1, reference numeral 1 denotes a steering mechanism. Between the steering mechanism 1 and the steering means 2, not the connecting means 4, but a rotation transmission ratio variable means 5 is interposed. Further, a steering angle changing motor M20 which is a steering actuator for changing the steering angle of the steering means 2 is attached to the column housing H3 instead of the reaction force motor M2, and the steering angle sensor 21 is not provided. A torque sensor 27 is provided below the steering angle changing motor M20. Between the torque sensor 27 and the rotation transmission ratio varying means 5, a separating means 6 for mechanically separating the upper and lower sides is provided. Are arranged. Further, the tie rods 13, 13 are not provided with the tie rod axial force sensor 18.
[0052]
The steering means 2 is connected to the upper end of the input shaft of the rotation transmission ratio variable means 5. The input shaft includes an upper shaft 20, a torsion bar 26, and a lower shaft 25, and a torque sensor 27 is disposed so as to surround a portion near a lower portion of the upper shaft 20 and a portion near an upper portion of the lower shaft 25. The output shaft 19 of the rotation transmission ratio variable means 5 is connected to the pinion shaft 14 via a universal joint 15c, an intermediate shaft 15b, and a universal joint 15a.
[0053]
FIG. 5 is a side sectional view schematically showing the configuration of the rotation transmission ratio variable means 5. The rotation transmission ratio variable means 5 includes a sun gear 53, a large-diameter ring gear 54 surrounding the outside of the sun gear 53 and having teeth on the inner and outer circumferences, and an annular ring between the sun gear 53 and the ring gear 54 in a cylindrical housing 50. A planetary gear transmission mechanism including a plurality of planetary gears 55, 55,... Which are equally arranged in space and mesh with the teeth of the sun gear 53 and the teeth of the inner periphery of the ring gear 54 is configured.
[0054]
The planetary gears 55, 55,... Are respectively held on a predetermined circumference of a disk-shaped carrier 56 so as to be able to rotate on their own, and the upper end of the output shaft 19 is coaxially connected to the carrier 56. ing. The sun gear 53 is connected to a lower end of the lower shaft 25. On the other hand, a pinion 57 of the output shaft of the transmission motor M3 fixed to the outer periphery of the housing 50 meshes with the teeth on the outer periphery of the ring gear 54, and the ring gear 54 rotates around the axis by the transmission from the transmission motor M3.
[0055]
The torque sensor 27 includes a magnetic target 27 a fixed to the lower end of the upper shaft 20, a magnetic target 27 b fixed to the upper end of the lower shaft 25, and an MR sensor that detects an adjacent portion of the target 27 a. A magnetoresistive effect element) 27c and an MR sensor 27d for detecting the proximity of the target 27b, and can detect the rotation angles of the upper shaft 20 and the lower shaft 25, respectively. The steering torque applied to the steering means 2 is detected based on the steering torque. The detection result is given to the steering control unit 3, and the rotation angle of each of the upper shaft 20 and the lower shaft 25 is "+" on the right rotation direction side from the neutral position, and "-" on the left rotation direction side from the neutral position. There is.
[0056]
The separating means 6 is attached to the lower shaft 25 and is constituted by an electromagnetic clutch or a friction clutch. Normally, it is in a connected state, and the lower shaft 25 is mechanically separated vertically by a separation signal from the steering control unit 3.
[0057]
With the above configuration, the vehicle steering system according to the third embodiment realizes a steering characteristic adapted to the running state in the manual mode, similarly to the conventional transmission ratio variable type steering system. In the automatic mode, the steering control unit 3 controls the driving of the steering motor M1 and the like based on the guidance signal detected by the guidance signal detection unit 24, thereby realizing automatic steering of the vehicle.
[0058]
Next, a case where the mode is changed from the automatic mode to the manual mode will be described with reference to a flowchart illustrating a process related to a mode change control performed by the steering control unit 3 according to the third embodiment. The description of the same parts as those in the flowchart of FIG. 2 in the first embodiment is omitted, and only different parts will be described below.
[0059]
In the flowchart of the first embodiment, the steering angle θ1 detected by the steering angle sensor 21 in S2 is read. In the third embodiment, the rotation of the upper shaft 20 detected by the torque sensor 27 in the step corresponding to S2. The angle (steering angle of the steering means 2) θ1 is read.
[0060]
In the step corresponding to S5, when the steering angle θ1 is different from the corresponding steering angle θ2 (S5, NO), the steering control unit 3 outputs a separation signal to the separation unit 6. Next, the steering control unit 3 adjusts the phase of the steering member 2 to the phase of the steered wheels 10, 10 in steps corresponding to S7 to S10.
[0061]
Next, the steering control unit 3 ends the output of the separation signal output to the separation unit 6, changes the mode to the manual mode in a step corresponding to S6, and ends the processing.
[0062]
As described above, when the occupant of the vehicle operates the mode change receiving unit 23 to change from the automatic mode to the manual mode, the steering control unit 3 controls the steering unit 2 and the steering unit 2 as described in the above-described flowchart. If the phases of the directional wheels 10, 10 are different, the steering means 2 and the input shaft are separated from the rotation transmission ratio variable means 5 by the separating means 6, and the steering means 2 is rotated to match the phases of the steered wheels 10, 10. After the phases are matched, the separating means 6 is stopped to return to the connected state. Therefore, when changing from the automatic mode to the manual mode, the phases of the steering means 2 and the steered wheels 10, 10 do not shift.
[0063]
As described above, in the third embodiment, the arrangement position of the steering motor M1 is not limited to the rack housing H1, and may be arranged at another position. Further, the rotation transmission ratio variable means 5 is a planetary gear transmission mechanism, but the rotation transmission mechanism is not limited to this, and another rotation transmission mechanism, for example, a planetary cone type rotation transmission mechanism or the like may be used.
[0064]
In the automatic mode corresponding to the AHS, even in a bad situation such as heavy rain, control for maintaining an appropriate speed, an inter-vehicle distance, and the like is performed, so that safety for traveling is ensured. On the other hand, whether or not the vehicle can run safely in the manual mode largely depends on the driver's attention and driving skill. For example, in a bad situation such as heavy rain, a slip may occur due to sudden steering or the like.
[0065]
Therefore, a rainfall detecting means for estimating or detecting the rainfall from the position of the intermittent time adjustment switch of the wiper or a rainfall sensor, and a running state sensor for detecting vehicle speed, presence or absence of acceleration / deceleration, yaw rate, and the like are provided. The detection result of the traveling state sensor is provided to the steering control unit. The steering control unit further includes a rainfall reading means for reading the detected rainfall, a rainfall comparing means for comparing the read rainfall with a predetermined threshold, a vehicle speed reading means for reading the detected vehicle speed, and a read vehicle speed and a predetermined threshold. By executing a program including a vehicle speed comparison unit that compares the vehicle speed and a steering assist suppression unit that instructs to reduce or stop applying the steering assist force, it is possible to prevent the vehicle from slipping.
[0066]
By performing processing and control as described below, vehicle slip can be prevented. The steering control unit reads the detection result of the rainfall detection unit, and compares the read detection result with a predetermined threshold by the rainfall comparison unit. When the detection result of the rainfall detecting means is equal to or more than a predetermined threshold, the steering control unit reads the vehicle speed detected by the traveling state sensor, and when the read vehicle speed is equal to or more than the predetermined threshold, the steering assist force is reduced by the steering assist suppressing means. Or stop granting. As a result, at a predetermined rainfall or more and at a predetermined vehicle speed or more, the steering torque is required to operate the steering means more than usual, and it becomes difficult to perform a sharp steering, so that it is possible to prevent the vehicle from slipping. it can.
[0067]
【The invention's effect】
As described in detail above, in the vehicle steering system according to the first invention, when changing from the automatic mode to the manual mode, if the phases of the steering means and the steered wheels are different, the steering means is rotationally driven. Since the phase is adjusted to the phase of the steered wheels, there is no phase shift between the steering means and the steered wheels, and the user does not feel uncomfortable in operating the steering means even after changing to the manual mode.
[0068]
Further, in the vehicle steering system according to the second aspect of the invention, the automatic mode can be changed to the manual mode only when the steered wheels are oriented in the straight traveling direction. There is no phase shift between the steering means and the steered wheels, so that the mode can be safely changed to the manual mode.
[0069]
Further, in the vehicle steering system according to the third invention, when changing from the automatic mode to the manual mode, if the phases of the steering means and the steered wheels are different, the steering means is rotationally driven to change the phase of the steered wheels. Since they are matched, there is no phase shift between the steering means and the steered wheels, and the user does not feel uncomfortable in operating the steering means even after changing to the manual mode.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a mechanical configuration of an embodiment of a vehicle steering system according to the present invention.
FIG. 2 is a flowchart of mode change control performed by a steering control unit when changing from an automatic mode to a manual mode.
FIG. 3 is a flowchart of mode change control performed by a steering control unit when changing from an automatic mode to a manual mode.
FIG. 4 is a schematic block diagram showing a mechanical configuration of an embodiment of the vehicle steering system according to the present invention.
FIG. 5 is a side sectional view schematically showing a configuration of a rotation transmission ratio variable unit.
[Explanation of symbols]
1 Steering mechanism
2 Steering means
3 Steering control unit
5 Rotation transmission ratio variable means
10,10 Steering wheel
16 Transmission shaft
17 Steering angle sensor
19 Output shaft
20 Column axis, upper axis
21 Steering angle sensor
23 Mode change reception section
27 Torque sensor
M1 steering motor (steering actuator)
M2 reaction motor (steering actuator)
M20 Steering angle changing motor (steering actuator)

Claims (3)

A steering mechanism for changing the direction of a steered wheel, a steering actuator for applying a driving force to the steering mechanism, and steering means connected to an upper part of a rotating shaft that is not mechanically connected to the steering mechanism. A steering angle sensor for detecting a steering angle of the steering means, a steering angle sensor for detecting a steering angle of the steered wheels, and the steering in accordance with a detection result of the steering angle sensor and the steering angle sensor. And a steering control unit that performs drive control of the actuator.
The steering control unit controls the steering in a manual mode for controlling the driving of the steering actuator in accordance with the steering of the steering means or in an automatic mode for controlling the driving of the steering actuator in accordance with an external guidance signal. With means,
A mode change receiving unit that receives a change instruction between the manual mode and the automatic mode,
A steering actuator that changes the steering angle of the steering means by applying a rotational force to the rotating shaft;
Reception determination means for determining whether the mode change reception unit has received an instruction to change from the automatic mode to the manual mode,
When the reception determining unit determines that the instruction has been received, based on the detection results of the steering angle sensor and the steering angle sensor, the steering angle of the steering unit corresponding to the steering angle of the steering unit and the steering angle of the steered wheel is determined. Identical determination means for determining whether the corresponding steering angle is the same,
When the same judging means judges no, the operation of the steering actuator is controlled to make the steering angle of the steering means correspond to the steering angle of the steering means corresponding to the turning angle of the steered wheel. A vehicle steering system comprising: a control unit. A steering mechanism for changing the direction of a steered wheel, a steering actuator for applying a driving force to the steering mechanism, and steering means connected to an upper part of a rotating shaft that is not mechanically connected to the steering mechanism. A steering angle sensor that detects a steering angle of the steered wheels, and a steering control unit that controls the steering of the steering unit and the drive control of the steering actuator according to the detection result of the steering angle sensor. In a vehicle steering system,
The steering control unit may be a manual mode for performing drive control of the steering actuator in accordance with steering of the steering means or the steering means may be in a neutral position, and may be driven in response to an external guidance signal to drive the steering actuator. Means for controlling steering in an automatic mode for controlling,
A mode change receiving unit that receives a change instruction between the manual mode and the automatic mode,
Reception determination means for determining whether the mode change reception unit has received an instruction to change from the automatic mode to the manual mode,
When the reception determination means determines that the instruction has been received, neutral determination means for determining whether the steering angle detected by the steering angle sensor is at a neutral position,
Changing means for changing from the automatic mode to the manual mode when the neutral determination means determines that the vehicle is in the neutral position. A steering mechanism connected to an upper portion of the input shaft, a steering mechanism for changing the direction of a steered wheel, an output shaft connected to the steering mechanism, and a rotation interposed between the input shaft and the output shaft. Transmission ratio variable means, a steering actuator for applying a driving force to the steering mechanism, a steering angle sensor for detecting a steering angle of the steering means, and the rotation transmission ratio variable in accordance with a detection result of the steering angle sensor. A steering control unit for controlling the change of the rotation transmission ratio of the means and controlling the drive of the steering actuator in accordance with the steering of the steering means.
The steering control unit controls the steering in a manual mode for controlling the driving of the steering actuator in accordance with the steering of the steering means or in an automatic mode for controlling the driving of the steering actuator in accordance with an external guidance signal. With means,
A mode change receiving unit that receives a change instruction between the manual mode and the automatic mode,
A turning angle sensor that detects a turning angle of the steered wheels;
A steering actuator that applies a rotational force to the input shaft to change a steering angle of the steering unit;
Reception determination means for determining whether the mode change reception unit has received an instruction to change from the automatic mode to the manual mode,
When the reception determining unit determines that the instruction has been received, based on the detection results of the steering angle sensor and the steering angle sensor, the steering angle of the steering unit corresponding to the steering angle of the steering unit and the steering angle of the steered wheel is determined. Identical determination means for determining whether the corresponding steering angle is the same,
When the same judging means judges no, the operation of the steering actuator is controlled to make the steering angle of the steering means correspond to the steering angle of the steering means corresponding to the turning angle of the steered wheel. A vehicle steering system comprising: a control unit.

Images