JP6131205B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a steer-by-wire vehicle steering apparatus.

  Recently, a steering device of a type called Steer By Wire has been developed. Patent Document 1 discloses a steering device for a vehicle of a steer-by-wire (SBW) system.

The SBW-type vehicle steering apparatus according to Patent Document 1 includes a setting unit that sets a steering angle ratio that is a ratio of a change in the turning angle of the steered wheel to a change in the steering angle of the steering wheel, and the turning angle of the steered wheel. Includes a steering angle controller that performs drive control of the steering actuator so as to obtain a target steering angle calculated based on the steering angle ratio and the steering angle set by the setting unit. The setting unit sets the steering angle ratio having such a characteristic that the steering angle ratio decreases as the steering angle absolute value increases, while having a region where the steering angle ratio is constant.
According to the vehicle steering control device of the SBW system according to Patent Literature 1, it is possible to appropriately perform the trajectory correction steering of the vehicle while reducing the uncomfortable feeling related to the steering given to the driver.

Patent Document 2 discloses a technique of an electric power steering device that steers a vehicle by transmitting a driving force of an electric motor according to a steering input to steered wheels. The driving force of the electric motor is transmitted to the steered wheels via a steered device that includes a worm gear and a worm wheel. Grease is sealed inside the casing of the steering apparatus having a grease return mechanism.
According to the electric power steering apparatus according to Patent Document 2, the lubricity can be maintained over a long period of time without deteriorating the startability by the grease hardened in the cold.

JP 2004-306717 A JP 2009-248724 A

  However, in the vehicle steering control device of the SBW system according to Patent Document 1, the viscosity of the grease that plays a role of lubrication related to the steering device becomes high at the start in a relatively low temperature environment such as winter. The friction related to the steering device increases. Then, there is a problem that the deviation between the target turning angle and the actual turning angle increases and the follow-up control performance is deteriorated.

  The present invention has been made in view of such circumstances, for example, control for causing the actual turning angle to follow the target turning angle even at the time of starting in a relatively low temperature environment. An object of the present invention is to provide a vehicle steering apparatus capable of maintaining performance as much as possible.

  In order to solve the above-mentioned problem, the invention according to (1) includes a steering member that is operated when turning a steered wheel of a vehicle, a steering angle detection unit that detects a steering angle related to the steering member, A steering mechanism that steers the steered wheels, the steered mechanism for steering the steered wheels in a state of being mechanically separated from the steering member; A steered angle detecting unit for detecting an angle, a steered torque correlation information acquiring unit for acquiring steered torque correlation information that is information correlated with steered torque required when steered wheels are steered, and the steering angle A steering angle ratio setting unit that sets a steering angle ratio that is a ratio of the steering angle to the steering wheel, and an actual steering angle of the steered wheels based on the steering angle ratio and the steering angle that are set by the steering angle ratio setting unit The steering actuator is controlled to follow the target turning angle calculated by Comprising a Cormorant controller, wherein the steering angle ratio setting unit, the steering angle ratio is set based on the steering torque correlation information, and the most important feature that.

  In the invention according to (1), the steering angle ratio setting unit correlates the steering angle ratio, which is the ratio of the steering angle with respect to the steering angle, to the steering torque required for turning the steered wheels. Set based on. The control unit calculates a target turning angle based on the steering angle ratio and the steering angle set by the steering angle ratio setting unit. Thereby, the target turning angle based on the steering angle ratio set to adapt to the magnitude of the friction related to the steering mechanism is obtained. The control unit controls the turning actuator so that the actual turning angle of the steered wheels follows the target turning angle thus calculated.

  According to the invention according to (1), for example, control performance for causing the actual turning angle to follow the target turning angle is maintained as much as possible even when starting in a relatively low temperature environment. can do.

  The invention according to (2) is the vehicle steering apparatus according to the invention according to (1), wherein the steering angle ratio setting unit has a torque threshold value at which the value of the steering torque correlation information is predetermined. When the value exceeds the steering angle ratio, the steering angle ratio is set to be smaller than a standard steering angle ratio that is set when the value of the steering torque correlation information is equal to or less than the torque threshold value.

  In the invention according to (2), when the value of the steering torque correlation information exceeds a predetermined torque threshold, the steering angle ratio is set as a standard rudder that is set when the value of the steering torque correlation information is equal to or less than the torque threshold. Set small relative to the angular ratio. Here, the torque threshold is determined in advance so as not to exceed the maximum torque of the steering actuator. If the value of the turning torque correlation information exceeds the maximum torque of the turning actuator, the control performance for causing the actual turning angle to follow the target turning angle is impaired, and an overcurrent flows through the turning actuator, resulting in an abnormality. This is because there is a risk of falling into a state.

  According to the invention according to (2), when the value of the steering torque correlation information exceeds a predetermined torque threshold, the steering angle ratio is set when the value of the steering torque correlation information is equal to or less than the torque threshold. In order to set small with respect to the standard rudder angle ratio, in addition to the function and effect of the invention according to (1), specific guidelines for maintaining the required control performance can be presented.

  The invention according to (3) is the vehicle steering device according to the invention according to (1) or (2), wherein the steering torque correlation information acquisition unit is based on environmental temperature information related to the vehicle. And obtaining the steering torque correlation information.

  In the invention which concerns on (3), a steering torque correlation information acquisition part acquires steering torque correlation information based on the environmental temperature information which concerns on a vehicle. Here, as environmental temperature information relating to the vehicle, for example, temperature information of grease enclosed in the steering mechanism, temperature information outside the vehicle, air conditioner operation information, seat heater temperature information, monitoring information of TPMS (Tire Pressure Monitoring System) Information relating to one or a plurality of combinations among tire air pressure information including, and weather information relating to an area including the current position of the vehicle may be adopted as appropriate. This is because the environmental temperature information related to such a vehicle correlates well with the magnitude of the turning torque required when turning the steered wheels.

  According to the invention according to (3), since the turning torque correlation information acquisition unit acquires the turning torque correlation information based on the environmental temperature information related to the vehicle, the operation of the invention according to (1) or (2) In addition to the effect, it is possible to contribute to the enrichment of acquisition routes related to the steering torque correlation information.

  The invention according to (4) is the vehicle steering apparatus according to the invention according to (1) or (2), wherein the steering torque correlation information acquisition unit is a steering drive that flows through the steering actuator. The steered torque correlation information is acquired based on information relating to current.

  In the invention which concerns on (4), a steering torque correlation information acquisition part acquires steering torque correlation information based on the information which concerns on the steering drive current which flows into a steering actuator. This is because the magnitude of the steering drive current flowing through the steering actuator correlates well with the magnitude of the steering torque required when the steered wheels are steered.

  According to the invention according to (4), the steering torque correlation information acquisition unit acquires the steering torque correlation information based on the information related to the steering drive current flowing in the steering actuator, so that (1) or (2 In addition to the operational effects of the invention according to), it is possible to contribute to the enrichment of acquisition routes related to the steering torque correlation information.

  The invention according to (5) is the vehicle steering device according to the invention according to (2), in which the steering angle ratio setting unit makes the steering angle ratio smaller than the standard steering angle ratio. In setting, the steering angle ratio is set to a characteristic that decreases as the steering angle increases.

  In the invention which concerns on (5), when setting a steering angle ratio small with respect to a standard steering angle ratio, a steering angle ratio setting part sets to the characteristic that a steering angle ratio becomes small as a steering angle becomes large. Thereby, even when the steering member is steered with a large steering angle, the steering angle ratio can be kept small. For this reason, the actual turning angle of the steered wheels can be kept small, and the load on the steered actuator can be reduced.

  According to the invention according to (5), it is possible to present specific and practical guidelines for maintaining the required control performance.

  The invention according to (6) is the vehicle steering device according to the invention according to (2), in which the steering angle ratio setting unit is configured such that when the steering angle exceeds a predetermined angle threshold, The steering angle ratio is set to be smaller than the standard steering angle ratio.

  In the invention which concerns on (6), a steering angle ratio setting part sets a steering angle ratio small with respect to a standard steering angle ratio, when a steering angle exceeds a predetermined angle threshold value. Here, the angle threshold value is appropriately set to a value having a slight margin in the neutral direction with respect to the lock angle. Thereby, even when the steering member is steered with a large steering angle exceeding the angle threshold, the steering angle ratio can be kept small. For this reason, the actual turning angle of the steered wheels can be kept small, and the load on the steered actuator can be reduced.

  According to the invention according to (6), it is possible to present specific and more practical guidelines for maintaining the required control performance.

  According to the present invention, for example, control performance for causing the actual turning angle to follow the target turning angle can be maintained as much as possible even at the time of starting in a relatively low temperature environment. .

1 is a schematic configuration diagram of a vehicle steering apparatus according to an embodiment of the present invention. FIG. 5 is a flowchart for explaining the operation of the vehicle steering device when an ignition switch of the vehicle is turned on.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a vehicle steering apparatus according to an embodiment of the present invention.
The vehicle steering apparatus 11 according to the embodiment of the present invention is a steer-by-wire (SBW) type steering apparatus. The vehicle steering device 11 generates a steering reaction force by driving a steering reaction force motor 16 to be described later and generates a steering force by driving a steering motor 29 to be described later (SBW mode), for example, a steering reaction force. When the motor 16 fails, an electric power steering (EPS) function (EPS mode) that generates an assisting force related to manual steering by the driver by driving the steering motor 29, and, for example, a steering reaction force When the motor 16 and the steered motor 29 fail, it has a function (manual steering mode) that allows the driver to perform manual steering.

  In order to realize the above functions, the vehicle steering device 11 includes a steering wheel 13, a steering reaction force generating device 15, a steering device 17, and a clutch mechanism 19, as shown in FIG. . The vehicle steering device 11 is mounted on the vehicle V. The vehicle V includes a pair of steered wheels 21a and 21b.

  The steering wheel 13 is a member that is operated in accordance with a driving intention related to the steering of the driver. The steering wheel 13 corresponds to the “steering member” of the present invention. A steering shaft 23 is provided on the steering wheel 13. The steering shaft 23 is configured to rotate around the axis in accordance with the operation of the steering wheel 13 by the driver.

  The steering reaction force generation device 15 has a function of generating a reaction force (response) related to steering at the driver's hand holding the steering wheel 13 when the vehicle steering device 11 is operating in the SBW mode. The steering reaction force generator 15 has a steering reaction force motor 16. A steering shaft 23 is connected to the steering reaction force motor 16. The steering reaction force motor 16 generates a steering torque for rotating the steering shaft 23 around the axis. As a result, when the vehicle steering device 11 is operating in the SBW mode, a reaction force (responsiveness) related to steering is transmitted to the driver's hand holding the steering wheel 13.

  The steered device 17 has a function of converting the rotational motion of the steered shaft 25 into the linear motion of the rack shaft 27 via a rack and pinion mechanism (not shown). The steering device 17 has a steering motor 29. The turning motor 29 corresponds to the “steering actuator” of the present invention. A steered shaft 25 and a rack shaft 27 are connected to the steered motor 29. The turning motor 29 generates a turning torque for causing the rack shaft 27 to linearly move along the axial direction. A pair of steered wheels 21a and 21b are connected to the rack shaft 27 via tie rods (not shown). The pair of steered wheels 21 a and 21 b are steered by a linear motion of the rack shaft 27.

  The steered device 17 having the steered shaft 25, the rack shaft 27, and the steered motor 29 corresponds to the “steering mechanism” of the present invention. Grease Gr is enclosed inside the casing of the steering device 17. Thereby, the lubricity between the machine elements including the rack and pinion mechanism housed in the housing of the steering device 17 is ensured.

  The clutch mechanism 19 has a function of connecting or disconnecting the steering shaft 23 and the steered shaft 25. In order to realize such a function, the clutch mechanism 19 includes a planetary gear mechanism 31. The planetary gear mechanism 31 includes an internal gear 31a, a planetary gear 31b, a sun gear 31c, and a planet carrier 31d. Grease Gr is also sealed inside the casing of the clutch mechanism 19. Thereby, the lubricity between the mechanical elements including the planetary gear mechanism 31 accommodated in the housing of the clutch mechanism 19 is ensured.

  The clutch mechanism 19 includes a locking gear 33 and a locking device 35. The lock device 35 includes a lock pin 39 that engages with a tooth groove of the lock gear 33, and an electromagnetic solenoid 37 that drives the lock pin 39.

  The internal gear 31 a is fixed to a side end portion of the steering device 17 in the steering shaft 23 and is configured to rotate integrally with the steering shaft 23. The sun gear 31c is configured to freely rotate around a rotation axis coaxial with the steered shaft 25. A plurality of planetary gears 31b are provided so as to engage with each of the sun gear 31c and the internal gear 31a. Each of the plurality of planetary gears 31b is rotatably supported with respect to a planet carrier 31d that rotates integrally with the steered shaft 25.

The locking gear 33 is an external gear. The locking gear 33 is configured to rotate integrally with the sun gear 31c. The lock pin 39 is urged in a direction close to the locking gear 33 by an urging means (not shown). When the lock pin 39 is engaged with the tooth groove of the locking gear 33, the rotational movement of the locking gear 33 is restricted.
The electromagnetic solenoid 37 operates to release the engagement between the lock pin 39 and the locking gear 33 by displacing the lock pin 39 by supplying the exciting current.
The locking device 35 is configured to operate according to a control signal sent from the control device 40. The control device 40 operates to release the engagement of the lock pin 39 with the locking gear 33 by supplying an excitation current to the electromagnetic solenoid 37.

Next, the operation of the clutch mechanism 19 will be described. When the lock pin 39 engages with the tooth groove of the locking gear 33, the rotational movement of the sun gear 31c that rotates together with the locking gear 33 is restricted.
When the driver operates the steering wheel 13 in a state where the rotational movement of the sun gear 31 c is restricted, the internal gear 31 a rotates with the rotation of the steering shaft 23. At this time, since the rotational movement of the sun gear 31c is restricted, the planetary gear 31b revolves around the sun gear 31c while rotating. By the revolution of the planetary gear 31b, the planetary carrier 31d that pivotally supports the planetary gear 31b and the turning shaft 25 that rotates together with the planetary carrier 31d rotate.

  In short, in a state where the lock pin 39 is engaged with the tooth groove of the locking gear 33, the clutch mechanism 19 is in a coupled state in which the steering shaft 23 and the steered shaft 25 are coupled. At this time, the rotational force of the steering shaft 23 is transmitted to the steered shaft 25.

On the other hand, when the engagement of the lock pin 39 with the tooth groove of the locking gear 33 is released, the sun gear 31c that rotates integrally with the locking gear 33 becomes rotatable.
When the driver operates the steering wheel 13 with the sun gear 31c being rotatable, the internal gear 31a is rotated with the rotation of the steering shaft 23. At this time, the planetary gear 31b tries to revolve around the sun gear 31c while rotating. However, the steered wheels 21 a and 21 b are connected to the planetary carrier 31 d via the steered shaft 25 and the rack shaft 27. For this reason, the resistance force against the rotation of the planet carrier 31d is much larger than the resistance force against the rotation of the sun gear 31c in a rotatable state. Therefore, when the planetary gear 31b rotates, the sun gear 31c rotates (rotates), and the planet carrier 31d does not rotate. That is, the steered shaft 25 does not rotate.

  In short, in a state where the engagement of the lock pin 39 with the tooth groove of the locking gear 33 is released, the clutch mechanism 19 is in a disconnected state in which the steering shaft 23 and the steered shaft 25 are disconnected. At this time, the rotational force of the steering shaft 23 is not transmitted to the steered shaft 25.

Next, an input / output system for the control device 40 will be described.
The control device 40 includes, as input systems, a steering angle sensor 41, a steering torque sensor 43, a steering reaction force motor resolver 45, a turning motor resolver 47, a rack stroke sensor 49, a grease temperature sensor 51, a turning drive current sensor 53, And the vehicle information terminal 55 is connected.

  The steering angle sensor 41 and the steering torque sensor 43 are provided on the steering shaft 23. The steering angle sensor 41 detects the steering angle of the steering wheel 13 by the driver, and gives the detected steering angle information to the control device 40. The steering angle sensor 41 corresponds to the “steering angle detector” of the present invention. Further, the steering torque sensor 43 detects the steering torque of the steering wheel 13 by the driver, and gives the detected steering torque information to the control device 40.

  The steering reaction force motor resolver 45 is provided in the steering reaction force motor 16. The steering reaction force motor resolver 45 detects the rotational operation amount (steering angle) of the steering reaction force motor 16 and supplies the detected steering angle information to the control device 40. Similarly to the steering angle sensor 41, the steering reaction force motor resolver 45 corresponds to the “steering angle detector” of the present invention.

  The steered motor resolver 47 is provided in the steered motor 29. The steered motor resolver 47 detects the rotational operation amount (steered angle) of the steered motor 29 and provides the detected steered angle information to the control device 40. The steered motor resolver 47 corresponds to the “steering angle detector” of the present invention.

  The rack stroke sensor 49 is provided on the rack shaft 27. The rack stroke sensor 49 detects the linear movement amount (steering angle) of the rack shaft 27 and provides the detected turning angle information to the control device 40. The rack stroke sensor 49 is also equivalent to the “steering angle detector” of the present invention, like the steered motor resolver 47.

The grease temperature sensor 51 detects the temperature of the grease Gr enclosed in the inside of the casing of the steering device 17, and uses the detected grease temperature information as a turning torque required for turning the steered wheels 21a and 21b. The information is given to the control device 40 as correlated information. The grease temperature information corresponds to “steering torque correlation information” of the present invention.
If the grease temperature sensor 51 is arranged in the vicinity of the rack and pinion mechanism for converting the rotational motion of the steered shaft 25 into the linear motion of the rack shaft 27, for example, inside the housing of the steered device 17. Good.

  The steered drive current sensor 53 detects the steered drive current flowing in the steered motor 29, and correlates the information related to the detected steered drive current with the steered torque required when the steered wheels 21a and 21b are steered. To the control device 40 as information to be performed. Information relating to the turning drive current corresponds to “steering torque correlation information” of the present invention.

  The in-vehicle information terminal 55 acquires, for example, weather information (including air temperature) related to the region including the current position of the vehicle via wireless communication via the antenna 57, and the weather information including the acquired air temperature is converted into a steered wheel. The information is given to the control device 40 as information correlating with the turning torque required when turning the wheels 21a and 21b. As the in-vehicle information terminal 55, for example, a smartphone or the like may be used as appropriate. Weather information including temperature corresponds to “steering torque correlation information” of the present invention.

  On the other hand, the control device 40 is connected to the steering reaction force motor 16, the steered motor 29, and the electromagnetic solenoid 37 as an output system.

  The control device 40 sets the steering mode of the vehicle steering device 11 to the SBW mode, the EPS based on the detection signal input via the input system and the abnormality diagnosis result related to various components of the vehicle steering device 11. A control signal for controlling the driving of the steering reaction force motor 16, the steering motor 29, and the electromagnetic solenoid 37 is generated in accordance with the function for determining the mode or the manual steering mode and the determined steering mode. And a function of performing drive control of the steering reaction force motor 16, the steered motor 29, and the electromagnetic solenoid 37 based on the generated control signal.

  The control device 40 controls the steering reaction force motor 16 when the vehicle steering device 11 is operating in the SBW mode, so that the driver's hand holding the steering wheel 13 can be appropriately steered. It operates to convey such reaction force (response).

  The control device 40 also steers the steered wheels 21a and 21b according to the driver's driving intention by performing drive control of the steered motor 29 when the vehicle steering device 11 is operating in the SBW mode. To work.

  Further, the control device 40 performs the drive control to switch the supply or stop of the excitation current to the electromagnetic solenoid 37 according to the steering mode of the vehicle steering device 11, thereby changing the state of the clutch mechanism 19 to the connected state or the disconnected state. It operates to switch to either one of the separated states.

  Then, the control device 40 has a function of acquiring the steering torque correlation information, a function of setting the steering angle ratio, which is a ratio of the steering angle to the steering angle, based on the acquired steering torque correlation information, It has a function of controlling the steered motor 29 so that the actual steered angles of the steered wheels 21a and 21b follow the target steered angle calculated based on the set steered angle ratio and steered angle. The control device 40 corresponds to the “control unit” of the present invention.

  In order to realize such various functions, the control device 40 includes a steering torque correlation information acquisition unit 61 and a steering angle ratio setting unit 63.

  The turning torque correlation information acquiring unit 61 has a function of acquiring turning torque correlation information. The steered torque correlation information is information correlated with steered torque required when steered wheels 21a and 21b are steered. As the turning torque correlation information, for example, turning torque detected by a turning torque sensor (not shown) itself, environmental temperature information related to the vehicle V, turning driving current detected by the turning drive current sensor 53 can be used. Such information can be adopted as appropriate.

  As the environmental temperature information related to the vehicle V, for example, the temperature information of the grease enclosed in the steering mechanism, the vehicle outside temperature information, the air conditioner operation information, the seat heater temperature information, the tire pressure information (the tire pressure is the environment related to the vehicle V) For example, weather information (including temperature) related to an area including the current position of the vehicle V can be exemplified.

The steering angle ratio setting unit 63 has a function of setting a steering angle ratio that is a ratio of a steering angle to a steering angle. Specifically, the steering angle ratio setting unit 63 operates to set the steering angle ratio based on the steering torque correlation information. Here, “setting the steering angle ratio based on the steering torque correlation information” means, for example, that the value of the steering torque correlation information depends on the magnitude of the value of the steering torque correlation information. The steering angle is smaller than the standard rudder angle ratio when the steering torque is over (heavy turning torque), and the standard rudder angle when the value of the turning torque correlation information is below the torque threshold (the turning torque is not heavy). The aspect which each sets a steering angle ratio is included so that it may become ratio.
The standard steering angle ratio means a standard steering angle ratio that is set when the value of the steering torque correlation information is equal to or less than the torque threshold (the steering torque is not heavy).

Next, the operation of the vehicle steering device 11 when an ignition switch (not shown) of the vehicle V is turned on will be described.
In the vehicle steering device 11 according to the embodiment of the present invention, it is assumed that the steering mode when the ignition switch of the vehicle V is turned on is the SBW mode in principle.

In step S11, the control device 40 checks whether or not the ignition switch of the vehicle V is turned on. As a result of the determination in step S11, if it is determined that the ignition switch of the vehicle V is not turned on (“No” in step S11), the control device 40 determines that the ignition switch of the vehicle V is turned on. The determination in step S11 is repeatedly performed until it is determined that it is present.
On the other hand, when it is determined that the ignition switch of the vehicle V is turned on as a result of the determination in step S11 (“Yes” in step S11), the control device 40 proceeds to the next step S12. Proceed to.

  In step S12, the steering torque correlation information acquisition unit 61 of the control device 40 acquires the value T1 of the steering torque correlation information based on the steering torque detected by the steering torque sensor.

In step S13, the control device 40 checks whether or not the value T1 of the steering torque correlation information acquired by the steering torque correlation information acquisition unit 61 exceeds a predetermined torque threshold Tth (the steering torque is heavy). As a result of the determination in step S13, when it is determined that the value T1 of the steering torque correlation information is equal to or less than the torque threshold Tth (the steering torque is not heavy) (“No” in step S13), the control device 40 Advances the process flow to the next step S14.
On the other hand, when it is determined that the value T1 of the steering torque correlation information exceeds the torque threshold Tth (the steering torque is heavy) as a result of the determination in step S13 ("Yes" in step S13), the control device 40 Causes the process flow to jump to step S15.

  In step S14, the steering angle ratio setting unit 63 of the control device 40 receives the determination result that the value T1 of the steering torque correlation information is equal to or less than the torque threshold Tth (the steering torque is not heavy). Is set to the standard steering angle ratio Pst.

  In step S15, in response to the determination result that the value T1 of the steering torque correlation information exceeds the torque threshold Tth (the steering torque is heavy), the steering angle ratio setting unit 63 of the control device 40 sets the steering angle ratio as a standard. Set smaller than the steering angle ratio Pst.

  In step S <b> 16, the control device 40 calculates a target turning angle based on the steering angle ratio and the steering angle set by the steering angle ratio setting unit 63.

  In step S17, the control device 40 controls the steered motor 29 so that the actual steered angles of the steered wheels 21a and 21b follow the target steered angle calculated in step S16. Such follow-up control of the turning motor 29 is performed in consideration of the fact that the deviation between the actual turning angle and the target turning angle is zero.

  After the process of step S17, the control device 40 returns the process flow to step S11, and sequentially performs the subsequent processes.

[Operational Effects of the Vehicle Steering Device 11 According to the Embodiment of the Present Invention]
In the vehicle steering device 11 based on the first aspect (corresponding to claim 1), a steering wheel (steering member) 13 that is operated when the steered wheels 21a and 21b of the vehicle V are steered, and a steering wheel (steering) Steering angle detectors 41 and 45 for detecting the steering angle related to the member 13 and steering motors (steering actuators) 29 for steering the steered wheels 21a and 21b, and a steering wheel (steering member). 13, turning device (steering mechanism) 17 for turning the steered wheels 21a, 21b in a state of being mechanically separated from each other, and turning angle detection for detecting the turning angle of the steered wheels 21a, 21b. Units 47 and 49, a steering torque correlation information acquisition unit 61 that acquires the steering torque correlation information that is information correlated with the steering torque required when the steered wheels 21a and 21b are steered, and the turning with respect to the steering angle. A steering angle ratio setting unit 63 that sets a steering angle ratio that is a ratio of angles, and a target that is calculated based on the steering angle ratio and the steering angle that are set by the steering angle ratio setting unit 63 for the actual turning angle of the steered wheels. And a control device (control unit) 40 that controls the turning motor (steering actuator) 29 so as to follow the turning angle.
The steering angle ratio setting unit 63 sets the steering angle ratio based on the steering torque correlation information.

  In the vehicle steering apparatus 11 based on the first aspect, the steering angle ratio setting unit 63 turns the steering angle required as the steering angle ratio, which is the ratio of the steering angle to the steering angle, when turning the steered wheels 21a and 21b. It sets based on the steering torque correlation information correlated with the torque. The control device (control unit) 40 calculates a target turning angle based on the steering angle ratio and the steering angle set by the steering angle ratio setting unit 63. Thereby, the target turning angle based on the steering angle ratio set to adapt to the magnitude of the friction related to the steering device (steering mechanism) 17 is obtained. The control device (control unit) 40 controls the steering motor (steering actuator) 29 so that the actual turning angle of the steered wheels follows the target turning angle thus calculated.

  According to the vehicle steering apparatus 11 based on the first aspect, for example, the control performance for causing the actual turning angle to follow the target turning angle even at the time of starting in a relatively low temperature environment. It can be maintained as much as possible.

  Further, in the vehicle steering apparatus 11 based on the second aspect (corresponding to claim 2), the steering angle ratio setting unit 63, when the value T1 of the steering torque correlation information exceeds a predetermined torque threshold Tth, A configuration in which the steering angle ratio is set smaller than the standard steering angle ratio Pst that is set when the value T1 of the steering torque correlation information is equal to or less than the torque threshold Tth may be employed.

  In the vehicle steering device 11 based on the second aspect, when the value T1 of the steering torque correlation information exceeds the torque threshold value Tth, the steering angle ratio is determined, and the value T1 of the steering torque correlation information is equal to or less than the torque threshold value Tth. Is set smaller than the standard rudder angle ratio Pst set at the time. Here, the torque threshold value Tth is determined in advance so as not to exceed the maximum torque of the turning motor (steering actuator) 29. If the value T1 of the turning torque correlation information exceeds the maximum torque of the turning motor 29, the control performance for causing the actual turning angle to follow the target turning angle is impaired, and an overcurrent is applied to the turning motor 29. This is because it may flow into an abnormal state.

  According to the vehicle steering apparatus 11 based on the second aspect, when the value T1 of the steering torque correlation information exceeds the torque threshold value Tth, the steering angle ratio is set as the steering torque correlation information value T1. In order to set it small with respect to the standard rudder angle ratio Pst set when Tth or less, in addition to the operational effects of the vehicle steering device 11 based on the first aspect, a specific for maintaining the required control performance Guidelines can be presented.

  In the vehicle steering apparatus 11 based on the third aspect (corresponding to claim 3), the steering torque correlation information acquisition unit 61 acquires the steering torque correlation information based on the environmental temperature information related to the vehicle V. The configuration may be adopted. Here, as environmental temperature information concerning the vehicle V, for example, temperature information of grease enclosed in the steering device (steering mechanism) 17, temperature information outside the vehicle, air conditioner operation information, seat heater temperature information, TPMS (Tire) Information relating to one or more combinations of tire pressure information including pressure monitoring system monitoring information and weather information (including temperature) relating to the area including the current position of the vehicle V may be appropriately employed. This is because such environmental temperature information related to the vehicle V correlates well with the magnitude of the turning torque required when turning the steered wheels 21a and 21b.

  According to the vehicle steering apparatus 11 based on the third aspect, the steering torque correlation information acquisition unit 61 acquires the steering torque correlation information based on the environmental temperature information related to the vehicle V. In addition to the operational effects of the vehicle steering device 11 based on this viewpoint, it is possible to contribute to the enrichment of acquisition routes related to the steering torque correlation information.

  In the vehicle steering apparatus 11 based on the fourth aspect (corresponding to claim 4), the turning torque correlation information acquisition unit 61 is information related to the turning drive current flowing in the turning motor (steering actuator) 29. A configuration in which the steering torque correlation information is acquired based on the above may be adopted. This is because the magnitude of the steering drive current flowing through the steering motor 29 correlates well with the magnitude of the steering torque required to steer the steered wheels 21a and 21b.

  According to the vehicle steering apparatus 11 based on the fourth aspect, the steering torque correlation information acquisition unit 61 acquires the steering torque correlation information based on the information related to the steering drive current flowing in the steering motor 29. In addition to the operational effects of the vehicle steering device 11 based on the first or second aspect, it is possible to contribute to the enrichment of acquisition routes related to the steering torque correlation information.

  In the vehicle steering device 11 based on the fifth aspect (corresponding to claim 5), the steering angle ratio setting unit 63 sets the steering angle ratio to be smaller than the standard steering angle ratio Pst. You may employ | adopt the structure set to the characteristic which a steering angle ratio becomes small as becomes large. Thereby, even when the steering wheel (steering member) 13 is steered with a large steering angle, the steering angle ratio can be kept small. For this reason, the actual turning angle of the steered wheels 21a and 21b is also reduced, and the load on the steered motor 29 can be reduced.

  According to the vehicle steering apparatus 11 based on the fifth aspect, it is possible to present a specific and practical guideline for maintaining the required control performance.

  In the vehicle steering apparatus 11 based on the sixth aspect (corresponding to claim 6), the rudder angle ratio setting unit 63 sets the rudder angle ratio to the standard rudder when the steering angle exceeds a predetermined angle threshold. A configuration in which the angle ratio Pst is set to be small may be employed.

  In the vehicle steering apparatus 11 based on the sixth aspect, the steering angle ratio setting unit 63 sets the steering angle ratio to be smaller than the standard steering angle ratio Pst when the steering angle exceeds a predetermined angle threshold. . Here, the angle threshold value is appropriately set to a value having a slight margin in the neutral direction with respect to the lock angle. Thereby, even when the steering wheel (steering member) 13 is steered with a large steering angle exceeding the angle threshold, the steering angle ratio can be kept small. For this reason, the actual turning angle of 21a, 21b is also suppressed small, and the load of the turning motor 29 can be reduced.

  According to the vehicle steering apparatus 11 based on the sixth aspect, it is possible to present a specific and more practical guideline for maintaining the required control performance.

[Other Embodiments]
The plurality of embodiments described above show examples of realization of the present invention. Therefore, the technical scope of the present invention should not be limitedly interpreted by these. This is because the present invention can be implemented in various forms without departing from the gist or main features thereof.

  For example, in the description according to the embodiment of the present invention, an example in which the clutch mechanism 19 having the planetary gear mechanism 31 is provided has been described, but the present invention is not limited to this example. The clutch mechanism 19 may have any configuration as long as the steering shaft 23 and the steered shaft 25 can be connected or disconnected.

  Further, in the description according to the embodiment of the present invention, the vehicle steering apparatus 11 has been described as an example having the SBW mode, the EPS mode, and the manual steering mode as the steering mode. However, the present invention is not limited to this example. It is not limited to. As the steering mode, the present invention may be applied to a vehicle steering apparatus having only the SBW mode (the steering shaft 23 and the steered shaft 25 are always disconnected).

  Finally, in the description according to the embodiment of the present invention, an example in which the magnitude of the steering angle ratio is set based on whether or not the value T1 of the steering torque correlation information exceeds one torque threshold value Tth will be given. Although described, the present invention is not limited to this example. A configuration may be adopted in which a plurality of values of the torque threshold Tth are provided, the range of the steering torque correlation information is divided into a plurality of values, and the magnitude of the steering angle ratio is set for each of a plurality of different value ranges.

11 Steering device for vehicle 13 Steering wheel (steering member)
17 Steering device (steering mechanism)
21a, 21b Steering wheel 25 Steering shaft (steering mechanism)
27 Rack shaft (steering mechanism)
29 Steering motor (steering mechanism)
41 Steering angle sensor (steering angle detector)
45 Steering reaction force motor resolver (steering angle detector)
47 Steering motor resolver (steering angle detector)
49 Rack stroke sensor (steering angle detector)
51 Grease temperature sensor 53 Steering drive current sensor 55 In-vehicle information terminal 61 Steering torque correlation information acquisition unit 63 Steering angle ratio setting unit V Vehicle

Claims (3)

A steering member operated when turning the steered wheels of the vehicle;
A steering angle detector that detects a steering angle of the steering member;
A steering mechanism that steers the steered wheels in a state in which the steered wheels are mechanically separated from the steering member;
A turning angle detector for detecting a turning angle associated with the steered wheel;
A steered torque correlation information acquisition unit for acquiring steered torque correlation information, which is information correlated with the steered torque required when the steered wheels are steered;
A steering angle ratio setting unit that sets a steering angle ratio that is a ratio of the steering angle to the steering angle;
Control for controlling the steered actuator so that the actual steered angle of the steered wheel follows the target steered angle calculated based on the steered angle ratio set by the steered angle ratio setting unit and the steered angle And comprising
The steered torque correlation information acquisition unit acquires the steered torque correlation information based on environmental temperature information related to the vehicle,
The steering angle ratio setting unit sets the steering angle ratio when the value of the steering torque correlation information exceeds a predetermined torque threshold, when the value of the steering torque correlation information is equal to or less than the torque threshold. Set to a smaller standard rudder angle ratio,
A vehicle steering apparatus characterized by the above. The vehicle steering device according to claim 1,
The rudder angle ratio setting unit sets the rudder angle ratio to a characteristic in which the rudder angle ratio decreases as the steering angle increases when the rudder angle ratio is set smaller than the standard rudder angle ratio.
A vehicle steering apparatus characterized by the above. The vehicle steering device according to claim 1 ,
The steering angle ratio setting unit sets the steering angle ratio to be smaller than the standard steering angle ratio when the steering angle exceeds a predetermined angle threshold;
A vehicle steering apparatus characterized by the above .

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