JP4544161B2 - Vehicle steering device - Google Patents

Description

  The present invention relates to a vehicle steering apparatus that turns a vehicle in response to a steering operation of a steering handle.

Conventionally, for example, as shown in Patent Document 1 below, it is detected that a wheel is in a hydroplaning state due to wetness of the road surface, and the vehicle is operated by steering the rear wheel in phase with the front wheel at the same time. 2. Description of the Related Art A vehicle steering device that is set to an understeer characteristic to improve the running stability of the vehicle in a hydroplaning state is known.
JP-A-8-324409

  However, in the above-mentioned conventional apparatus, it is a countermeasure after the occurrence of the hydroplaning phenomenon, and the occurrence of the hydroplaning phenomenon cannot be suppressed.

  The present invention has been made to address the above-described problems, and an object of the present invention is to provide a vehicle steering apparatus that suppresses the occurrence of a hydroplaning phenomenon.

  In order to achieve the above object, the present invention is characterized in that a rear wheel steering means capable of turning a rear wheel in a vehicle steering apparatus for turning a vehicle by turning a front wheel in accordance with a steering operation of a steering wheel. Road surface wet state determining means for determining whether or not the road surface is wet; and rear wheel turning angle determining means for determining the rear wheel turning angle so that the rear wheel locus is the same as the front wheel locus; A rear wheel turning control means for controlling the rear wheel turning means so that the turning angle of the rear wheel becomes the determined turning angle when the road surface wet state judgment means determines that the road surface is in a wet state. Be prepared. In this case, for example, the vehicle steering apparatus further includes a vehicle speed sensor that detects the vehicle speed, and the rear wheel steering control means has a vehicle speed detected by the vehicle speed sensor in addition to the road surface being wet. On the condition of the above, it is preferable to allow the rear wheels to be steered by the rear wheel steering means.

  In the feature of the present invention configured as described above, when the road surface is wet, the trajectories of the front wheels and the rear wheels are the same, that is, the rear wheels pass through the same place as the front wheels. Accordingly, the rear wheel passes through a thin road surface of water film from which water has been pushed away by the front wheel, and at least the rear wheel is less likely to cause a hydroplaning phenomenon. Further, by adding that the vehicle speed is equal to or higher than the predetermined vehicle speed to the rear wheel steering control condition, unnecessary rear wheel steering can be avoided.

  Another feature of the present invention is that the front wheel steering means that can independently steer the left and right front wheels and the front wheel steering means according to the steering operation of the steering handle, the left and right front wheels are steered by the steering handle. A road surface for determining whether the road surface is wet or not in a vehicle steering apparatus that turns the vehicle according to a steering operation of a steering handle. When the wet state determination means and the road surface wet state determination means determine that the road surface is in a wet state, the turning angle of the left and right front wheels according to the steering operation of the steering wheel by the front wheel steering control means is corrected in the toe-out direction. A to-out correction means is provided. In this case, for example, the vehicle steering apparatus further includes a vehicle speed sensor that detects the vehicle speed, and the toe out correction means has a vehicle speed detected by the vehicle speed sensor equal to or higher than a predetermined vehicle speed in addition to the road surface being wet. Under certain conditions, the turning angle of the left and right front wheels may be corrected in the toe-out direction.

  In another aspect of the present invention configured as described above, when the road surface is in a wet state, the front wheels are steered in the toe-out direction, the width of the heel of the front wheels is increased, and the water film is thin and wide. The heel is formed by the front wheels. Accordingly, the rear wheel passes through the thin ridge portion of the water film formed by the front wheel, and at least the rear wheel is less likely to cause a hydroplaning phenomenon. Further, by adding that the vehicle speed is equal to or higher than the predetermined vehicle speed to the front wheel toe-out correction control condition, unnecessary front wheel toe-out correction can be avoided.

a. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic diagram of a vehicle steering apparatus according to the first embodiment.

  The vehicle steering apparatus includes a steering handle 10 that is steered by a driver. The steering handle 10 is connected to the upper end of the steering shaft 11 so as to rotate integrally with the steering handle 10. A pinion gear 12 is provided at the lower end of the steering shaft 11 so as to rotate integrally with the steering shaft 11. The pinion gear 12 meshes with rack teeth 13a provided on the rack bar 13, and the rack bar 13 is driven in the axial direction by the rotation thereof. The rack bar 13 connects the left and right front wheels FW1 and FW2 as steered wheels via a tie rod and a knuckle arm (not shown) at both ends so as to be steerable, and steers the left and right front wheels FW1 and FW2 by axial displacement. To do.

  In this vehicle steering apparatus, the left and right rear wheels RW1, RW2 are also steered by an electric motor 20 as an electric actuator. The electric motor 20 is assembled on the outer periphery of the rear wheel turning shaft 21. The rear wheel turning shaft 21 is connected to the left and right rear wheels RW1 and RW2 as steered wheels via a tie rod and a knuckle arm (not shown) at both ends so that the left and right rear wheels RW1 and RW1 can be steered. Steer RW2. The rotation of the electric motor 20 is transmitted to the rear wheel turning shaft 21 via a ball screw feed mechanism 22 assembled on the outer periphery of the rear wheel turning shaft 21. The ball screw mechanism 22 decelerates the rotation of the electric motor 20, converts it into a linear motion, and transmits it to the rear wheel turning shaft 21.

  Next, an electric control device that controls the electric motor 20 will be described. The electric control device includes a rear wheel turning angle sensor 31, a vehicle speed sensor 32, a yaw rate sensor 33, and a road surface wetness sensor 34. The rear wheel turning angle sensor 31 is constituted by a rotation angle sensor incorporated in the electric motor 20, and detects the turning angle θr of the left and right rear wheels RW1 and RW2 by detecting the rotation angle of the electric motor 20. Note that the rear wheel turning angle θr represents the left and right rear wheels RW1 and RW2 as negative values, with the neutral position of the left and right rear wheels RW1 and RW2 being “0”, and the left and right rear wheels RW1 and RW2. The steering angle in the right direction is expressed as a positive value. Further, instead of the rear wheel turning angle sensor 31, a sensor that detects the turning angle θr of the left and right rear wheels RW1 and RW2 by displacement in the axial direction of the rear wheel turning shaft 21 may be used.

  The vehicle speed sensor 32 detects the vehicle speed V. The yaw rate sensor 33 detects the yaw rate γ around the center of gravity of the vehicle body. The road surface wetness sensor 34 detects the wet state of the traveling road surface of the vehicle. For example, the road surface wetness sensor 34 detects the wet state based on whether or not the wiper is operated. Specifically, it is detected that the road surface is not wet when the wiper is not operated, and it is detected that the road surface is wet when the wiper is operated. As the road surface wetness sensor 34, a raindrop sensor that detects the wet state of the road surface by detecting the presence or absence of rain, an image sensor that captures an image of the road surface and detects the wet state of the road surface from the captured image, and the like are used. May be.

  These rear wheel turning angle sensor 31, vehicle speed sensor 32, yaw rate sensor 33, and road surface wetness sensor 34 are connected to an electronic control unit (hereinafter referred to as ECU) 35. The ECU 35 has a microcomputer composed of a CPU, ROM, RAM, and the like as main components, and detects the sensors 31 to 34 by repeatedly executing the rear wheel steering program shown in FIG. 2 every predetermined short time. The electric motor 20 is driven and controlled via the drive circuit 36 in accordance with the signal.

  Next, the operation of the first embodiment configured as described above will be described. By turning on the ignition switch, the ECU 35 starts to repeatedly execute the rear wheel steering program shown in FIG. 2 every predetermined short time. The execution of the rear wheel steering program is started in step S10, and the ECU 35 inputs the vehicle speed V detected by the vehicle speed sensor 32 in step S11, and determines whether or not the detected vehicle speed V is equal to or higher than the predetermined vehicle speed V1. . This determination process determines whether the vehicle is traveling at high speed, and the predetermined vehicle speed V1 is set in advance to a value of about 40 to 60 km / h, for example.

  If the vehicle is not traveling at high speed, the ECU 35 determines “No” in step S11 and proceeds to step S13. In step S13, the detected rear wheel turning angle θr from the rear wheel turning angle sensor 31 is input, and the detected rear wheel turning angle θr is “0”, that is, the left and right rear wheels RW1 and RW2 are in the neutral position. Drive control of the motor 20 is performed. Of course, when the left and right rear wheels RW1 and RW2 are originally in the neutral position, the left and right rear wheels RW1 and RW2 are kept in the neutral position without controlling the drive of the electric motor 20. And in step S17, execution of this rear-wheel steering program is once complete | finished.

  If the vehicle is traveling at a high speed and the detected vehicle speed V is equal to or higher than the predetermined vehicle speed V1, the ECU 35 determines “Yes” in step S11 and proceeds to step S12. In step S12, a detection signal indicating the wet state of the road surface from the road surface wetness sensor 34 is input to determine whether or not the road surface is wet. If the road surface is not wet, the ECU 35 determines “No” in step S12, and executes the process of step S13 described above. As a result, when the road surface is not wet, the left and right rear wheels RW1, RW2 are kept in the neutral position.

なお、上記式１中の値Ｃは、車両の重心位置からホイルベース中点までの距離を表す車両に応じて予め決められた定数である。なお、ホイルベース中点とは、車両の重心位置を通る前後軸上の点であって、左右前輪ＦＷ１，ＦＷ２の中心位置を結ぶ前輪軸までの距離と左右後輪ＲＷ１，ＲＷ２の中心位置を結ぶ後輪軸までの距離とが等しい点である。 On the other hand, if the vehicle is traveling at high speed and the road surface is wet, the ECU 35 determines “Yes” in steps S11 and S12, and executes the processes of steps S14 and S15. In step S14, the detected yaw rate γ is inputted from the yaw rate sensor 33, and the left and right front wheels FW1 and FW2 and the left and right rear are executed by executing the calculation of the following equation 1 using the inputted detected yaw rate γ and the inputted detected vehicle speed V. A target side slip angle β of the vehicle body for matching the trajectories of the wheels RW1 and RW2 is calculated.

Note that the value C in the above equation 1 is a constant determined in advance according to the vehicle representing the distance from the center of gravity position of the vehicle to the wheel base midpoint. The wheel base midpoint is a point on the front-rear axis that passes through the center of gravity of the vehicle, and connects the distance to the front wheel axis that connects the center positions of the left and right front wheels FW1, FW2 and the center position of the left and right rear wheels RW1, RW2. This is the point where the distance to the rear wheel axle is equal.

なお、前記式２中の値Ｌｒは、車両の重心位置から左右後輪ＲＷ１，ＲＷ２の中心位置を結ぶ後輪軸までの距離を表す車両に応じて予め決められた定数である。値Ｃｐは、左右後輪ＲＷ１,ＲＷ２のコーナリングパワーを左右後輪ＲＷ１,ＲＷ２の軸重で正規化したコーナリングパワーを表す車両に応じて予め決められた定数である。 In step S15, the left and right rear wheels RW1 and RW2 are changed to the left and right front wheels FW1 and FW2 by executing the calculation of the following equation 2 using the calculated target skid angle β and the input detected yaw rate γ and detected vehicle speed V. A target rear wheel turning angle θr * for passing through the same place is calculated.

The value Lr in Equation 2 is a constant determined in advance according to the vehicle representing the distance from the center of gravity position of the vehicle to the rear wheel axis connecting the center positions of the left and right rear wheels RW1, RW2. The value Cp is a constant determined in advance according to the vehicle representing the cornering power obtained by normalizing the cornering power of the left and right rear wheels RW1 and RW2 by the axial weight of the left and right rear wheels RW1 and RW2.

  After the processing of steps S14 and S15, the ECU 35 inputs the detected rear wheel turning angle θr from the rear wheel turning angle sensor 31 in step S16, and the detected rear wheel turning angle θr is calculated as the calculated target rear wheel turning angle. The electric motor 20 is driven and controlled to be equal to θr *. By this drive control, the electric motor 20 rotates and drives the rear wheel steering shaft 21 in the axial direction via the ball screw mechanism 22. As a result, the left and right rear wheels RW1, RW2 are steered to the target rear wheel turning angle θr *. And in step S17, execution of this rear-wheel steering program is complete | finished.

  As can be understood from the above description of the operation, according to the first embodiment, step S14 is performed under the condition that the vehicle is traveling at high speed and the road surface is in a wet state by the determination processing in steps S11 and S12. Through the processing of S16, the left and right rear wheels RW1, RW2 pass through the same place as the left and right front wheels FW1, FW2, as indicated by the solid line in FIG. In FIG. 3B, the locus of the left and right front wheels FW1 and FW2 when the left and right rear wheels RW1 and RW2 are not steered is indicated by a solid line, and the locus of the left and right rear wheels RW1 and RW2 is indicated by a broken line. Therefore, the left and right rear wheels RW1 and RW2 pass through a thin road surface of the water film from which water has been pushed away by the left and right front wheels FW1 and FW2, and at least the left and right rear wheels RW1 and RW2 are less likely to cause hydroplaning. Further, since the vehicle speed V is equal to or higher than the predetermined vehicle speed V1, that is, the vehicle is traveling at high speed, the steering control condition for the left and right rear wheels RW1 and RW2 is used, so unnecessary steering of the left and right rear wheels RW1 and RW2 is avoided. it can.

b. Second Embodiment Next, a second embodiment of the present invention will be described. FIG. 4 is an overall schematic diagram of the vehicle steering apparatus according to the second embodiment, and the left and right front wheels FW1, FW2 can be steered independently. In FIG. 4, the same members and components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The left and right front wheels FW1, FW2 are mechanically separated from the steering handle 10 and supported by a vehicle body (not shown) so as to be steerable by arm mechanisms 41, 42, respectively. Although not shown in the present invention since it is not directly related to the present invention, a reaction force actuator is assembled to the steering shaft 11 connected to the steering handle 10, and the reaction force actuator counteracts the steering operation of the steering handle 10. Power is given.

  The rear end portions of the arm mechanisms 41 and 42 are driven left and right by drive actuators 45 and 46 by electric actuators 43 and 44, respectively. The electric actuators 43 and 44 have, in their housings, an electrically driven electric motor and a conversion mechanism that reduces the rotational motion of the electric motor and converts it into linear motion. The inner end is driven left and right via pins 45a and 46a that are rotatably engaged with the drive rods 45 and 46. The drive rods 45, 46 are displaced in the left-right direction while swinging by driving by the electric actuators 43, 44 so that the rear end portions of the arm mechanisms 41, 42 can be rotated with respect to the drive rods 45, 46. It is driven left and right via the engaged pins 45b and 46b. Accordingly, the left and right front wheels FW1 and FW2 are steered independently by the electric actuators 43 and 44, respectively.

  The left and right rear wheels RW1, RW2 are supported by the vehicle body (not shown) by the arm mechanisms 47, 48, but are not steered. That is, in the second embodiment, the left and right rear wheels RW1, RW2 are always kept in the neutral position. In the second embodiment, the left and right rear wheels RW1 and RW2 are not steered, but they are not prohibited from being steered and may be steerable.

  Next, an electric control device that controls the electric actuators 43 and 44 will be described. The electric control device includes a steering wheel steering angle sensor 51, a left front wheel turning angle sensor 52, a right front wheel turning angle sensor 53, and a vehicle height sensor in addition to the vehicle speed sensor 32, the yaw rate sensor 33, and the road surface wetness sensor 34 of the first embodiment. 54a-54d. The steering wheel steering angle sensor 51 is assembled to the steering shaft 11 and detects a steering wheel steering angle θh that is a rotation angle of the steering wheel 10. The steering wheel steering angle θh is set to “0” as the neutral position of the steering wheel 10, the left rotation angle of the steering wheel 10 is expressed as a negative value, and the right rotation angle of the steering handle 10 is expressed as a positive value. To express.

  The left front wheel turning angle sensor 52 and the right front wheel turning angle sensor 53 are respectively constituted by rotation angle sensors incorporated in the electric motors in the electric actuators 43 and 44, and the left and right front wheels FW1 are detected by detecting the rotation angle of each electric motor. , FW2 left and right front wheel turning angles θf1 and θf2 are detected. The left and right front wheel turning angles θf1 and θf2 are also represented by “0” as the neutral position of the left and right front wheels FW1 and FW2, and the leftward turning angles of the left and right front wheels FW1 and FW2 are represented by negative values. The steering angle in the right direction is expressed as a positive value. Further, instead of these left front wheel turning angle sensor 52 and right front wheel turning angle sensor 53, sensors that detect the left and right front wheel turning angles θf1 and θf2 by the displacement of the arm mechanisms 41 and 42 or the drive rods 43 and 44 are used. Also good.

  The vehicle height sensors 54a to 54d detect the vehicle heights h1 to h4 at the positions of the left and right front wheels FW1 and FW2 and the left and right rear wheels RW1 and RW2, respectively. These sensors 32 to 34, 51 to 53, and 54a to 54d are connected to the ECU 35. The ECU 35 has the same configuration as that of the first embodiment, but the sensors 32 to 34, 51 to 53, 54a, etc. are repeatedly executed by repeatedly executing the front wheel turning program of FIG. 5 every predetermined short time. The electric actuators 43 and 44 are driven and controlled via the drive circuits 55 and 56 in accordance with the detection signal 54d.

  Next, the operation of the second embodiment configured as described above will be described. By turning on the ignition switch, the ECU 35 starts to repeatedly execute the front wheel steering program shown in FIG. 4 every predetermined short time. Execution of the front wheel steering program is started in step S20, and the ECU 35 detects the detected vehicle speed V equal to or higher than the predetermined vehicle speed V1, that is, the vehicle is detected by the determination processing in steps S21 and 22 similar to steps S11 and S12 in the first embodiment. It is determined whether the vehicle is running at high speed and whether the road surface is wet.

なお、前記式３，４中の値Ｋは、ハンドル操舵角θｈに対する左右前輪ＦＷ１，ＦＷ２の操舵角の比を表す車両に応じて予め定められた所定の定数である。 If the vehicle is not in a high-speed running state or the road surface is not wet, the ECU 35 determines “No” in step S21 or S22 and proceeds to step S23. In step S23, the steering wheel steering angle θh is input from the steering wheel steering angle sensor 51, and the target left front wheel turning angle θf1 * and the target right front wheel turning angle θf2 * are calculated by executing the calculations of the following equations 3 and 4.

The value K in the equations 3 and 4 is a predetermined constant that is predetermined according to the vehicle and represents the ratio of the steering angle of the left and right front wheels FW1 and FW2 to the steering wheel steering angle θh.

  After the process of step S23, the ECU 35 inputs the detected left front wheel turning angle θf1 from the left front wheel turning angle sensor 52 in step S30, and also inputs the detected right front wheel turning angle θf2 from the right front wheel turning angle sensor 53, The electric actuators 43 and 44 are driven and controlled so that the detected left front wheel turning angle θf1 and the detected right front wheel turning angle θf2 are equal to the calculated target left front wheel turning angle θf1 * and target right front wheel turning angle θf2 *, respectively. By this drive control, the electric actuators 43 and 44 rotate the arm mechanisms 41 and 42 via the drive rods 45 and 46, respectively. As a result, the left and right front wheels FW1, FW2 are steered to the target left front wheel turning angle θf1 * and the target right front wheel turning angle θf2 *. And in step S31, execution of this front-wheel steering program is complete | finished.

  On the other hand, if the vehicle is in a high-speed running state and the road surface is wet, the ECU 35 determines “Yes” in steps S21 and S22, and executes the processes in steps S24 and S25. In step S24, the detected vehicle heights h1 to h4 at the positions of the left and right front wheels FW1 and FW2 and the left and right rear wheels RW1 and RW2 are input from the vehicle height sensors 54a to 54d, respectively, and the detected vehicle heights h1 to h4 are used. The center of gravity height h is calculated. In the calculation of the center of gravity height h of the vehicle, the average value of the detected vehicle heights h1 to h4 is set as the center of gravity height h of the vehicle.

なお、上記式５，６中の値Ｇは、制御ゲインを表す左右前輪ＦＷ１，ＦＷ２を転舵するための機構に応じて予め決められた定数である。値λは、左右前輪ＦＷ１，ＦＷ２の過重配分を表す車両に応じて予め決められた定数である。値ｇは、重力加速度を表す予め決められた定数である。値Ｔは、トレッドを表す車両に応じて予め決められた定数である。値ζは、左右前輪ＦＷ１，ＦＷ２のロール剛性配分を表す車両に応じて予め決められた定数である。 In step S25, the detected yaw rate γ is input from the yaw rate sensor 33, and using the detected yaw rate γ, the detected vehicle speed V input by the processing in step S21, and the calculated center of gravity height h, By executing this calculation, the toe-out angle δa of the turning inner wheel and the toe-out angle δb of the turning outer wheel for allowing the left and right rear wheels RW1, RW2 to pass through the inside of the left and right front wheels FW1, FW2 are calculated.

The value G in the above formulas 5 and 6 is a constant determined in advance according to the mechanism for turning the left and right front wheels FW1 and FW2 representing the control gain. The value λ is a constant determined in advance according to the vehicle representing the over-weight distribution of the left and right front wheels FW1, FW2. The value g is a predetermined constant representing the gravitational acceleration. The value T is a constant determined in advance according to the vehicle representing the tread. The value ζ is a constant determined in advance according to the vehicle representing the roll stiffness distribution of the left and right front wheels FW1, FW2.

  After the processes in steps S24 and S25, the ECU 35 determines whether the vehicle is turning left or right in steps S26 and S27, respectively. That is, in step S26, it is determined whether the vehicle is turning left by inputting the steering wheel steering angle θh from the steering wheel steering angle sensor 51 and determining whether the steering wheel steering angle θh is negative. In step S27, it is determined whether the vehicle is turning right by determining whether the input steering angle θh is positive.

If the vehicle is turning left and the steering wheel steering angle θh is negative, “Yes” is determined in step S26, and the process proceeds to step S28. In step S28, by using the input steering wheel steering angle θh, the calculated toe-out angle δa of the turning inner wheel, and the toe-out angle δb of the turning outer wheel, the calculation of the following formulas 7 and 8 is performed to calculate the target left front wheel turning angle θf1. * And target right front wheel turning angle θf2 * are calculated respectively.

On the other hand, if the vehicle is turning right and the steering wheel steering angle θh is positive, “Yes” is determined in step S27, and the process proceeds to step S29. In step S29, using the input steering wheel steering angle θh, the calculated toe-out angle δa of the turning inner wheel, and the toe-out angle δb of the turning outer wheel, the calculation of the following formulas 9 and 10 is performed to calculate the target left front wheel turning angle θf1. * And target right front wheel turning angle θf2 * are calculated respectively.

  Further, if the vehicle is in a straight traveling state and the steering wheel steering angle θh is “0”, “No” is determined in steps S26 and S27, respectively, and the target left front wheel turning angle θf1 is determined by the processing in step S23 described above. * And target right front wheel turning angle θf2 * are calculated respectively.

  Then, after the processes of steps S28, S29, and S23, the ECU 35 calculates the target left front wheel turning angle θf1 * calculated by the processes of steps S28, S29, and S23 for the left and right front wheels FW1 and FW2 by the process of step S30 described above. Turn to the target right front wheel turning angle θf2 *. And in step S31, execution of this front-wheel steering program is complete | finished.

  As can be understood from the above description of operation, according to the second embodiment, the conditions that the vehicle is traveling at a high speed and the road surface is in a wet state are determined by the determination processing in steps S21, S22, S26, and S27. Below, the left and right front wheels FW1 and FW2 pass through the insides of the left and right rear wheels RW1 and RW2 as shown by the thick arrows in FIG. 6A by the processing of steps S24, S25, S28, and S29. Further, the steering of the left and right front wheels FW1 and FW2 by the steering operation of the steering handle 10 is steered by δa and δb extra to the toe-out side. In FIG. 6 (B), the arrows of the left and right front wheels FW1 and FW2 when the left and right front wheels FW1 and FW2 are not steered to the toe-out side are indicated by thick arrows. Therefore, the left and right rear wheels RW1 and RW2 pass through the thin ridges of the water film from which water has been pushed away by the left and right front wheels FW1 and FW2, and at least the left and right rear wheels RW1 and RW2 are less likely to cause hydroplaning. . Further, by adding that the vehicle speed V is equal to or higher than the predetermined vehicle speed V1, that is, that the vehicle is traveling at high speed, to the toe-out correction control conditions for the left and right front wheels FW1 and FW2, unnecessary toe-out correction for the left and right front wheels FW1 and FW2 is performed. Can be avoided.

  Furthermore, the present invention is not limited to the first and second embodiments, and various modifications can be employed within the scope of the present invention.

1 is an overall schematic diagram of a vehicle steering apparatus according to a first embodiment of the present invention. It is a flowchart which shows the rear-wheel steering program performed by ECU of FIG. (A) is explanatory drawing for demonstrating the locus | trajectory of the front wheel and rear wheel by the steering apparatus of the vehicle which concerns on the said 1st Embodiment, (B) is the locus | trajectory of the front wheel and rear wheel when not turning a rear wheel. It is explanatory drawing for demonstrating. It is a whole schematic diagram of the steering device of vehicles concerning a 2nd embodiment of the present invention. It is a flowchart which shows the front-wheel steering program performed by ECU of FIG. (A) is explanatory drawing for demonstrating the saddle of the front wheel by the steering apparatus of the vehicle which concerns on the said 2nd Embodiment, (B) is description for demonstrating the saddle of the front wheel in case the front wheel is not independently steered. FIG.

Explanation of symbols

FW1, FW2 ... left and right front wheels, RW1, RW2 ... left and right rear wheels, 10 ... steering handle, 20 ... electric motor, 31 ... rear wheel turning angle sensor, 32 ... vehicle speed sensor, 33 ... yaw rate sensor, 34 ... road surface wetness sensor, 35 ... an electronic control unit (ECU), 43, 44 ... an electric actuator, 51 ... a steering wheel steering angle sensor, 52 ... a left front wheel turning angle sensor, 53 ... a right front wheel turning angle sensor.

Claims (4)

In a vehicle steering apparatus for turning a vehicle by turning a front wheel according to a steering operation of a steering handle,
Rear wheel steering means capable of steering the rear wheels;
Road surface wet state determination means for determining whether or not the road surface is wet;
Rear wheel turning angle determining means for determining the turning angle of the rear wheel so that the locus of the rear wheel is the same as the locus of the front wheel;
Rear wheel turning control means for controlling the rear wheel turning means so that the turning angle of the rear wheels becomes the determined turning angle when the road surface wet state judging means determines that the road surface is wet. A vehicle steering apparatus comprising the vehicle. The vehicle steering apparatus according to claim 1, further comprising:
It has a vehicle speed sensor that detects the vehicle speed,
The rear wheel steering control means steers rear wheels by the rear wheel steering means on condition that the road surface is wet and the vehicle speed detected by the vehicle speed sensor is equal to or higher than a predetermined vehicle speed. Vehicle steering device that allows Front wheel steering means that can steer the left and right front wheels independently,
Front wheel steering control means for controlling the front wheel steering means according to the steering operation of the steering handle, and for turning the left and right front wheels to a steering angle according to the steering operation of the steering handle,
In a vehicle steering apparatus for turning a vehicle in response to a steering operation of a steering handle,
Road surface wet state determination means for determining whether or not the road surface is wet;
A toe-out correction that corrects the turning angle of the left and right front wheels in the toe-out direction according to the steering operation of the steering wheel by the front wheel steering control means when the road surface wet state judging means judges that the road surface is wet. And a vehicle steering apparatus. The vehicle steering apparatus according to claim 3, further comprising:
It has a vehicle speed sensor that detects the vehicle speed,
The toe-out correction means corrects the turning angle of the left and right front wheels in the toe-out direction on condition that the road surface is wet and the vehicle speed detected by the vehicle speed sensor is equal to or higher than a predetermined vehicle speed. Steering device.

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