JP5618014B2 - Steering device - Google Patents

Description

  The present invention relates to a steering apparatus, and more particularly to a steering apparatus provided with a transmission ratio variable mechanism.

  Conventionally, a transmission ratio variable device that changes a transmission ratio, which is a ratio of a wheel turning angle to a steering angle of a steering wheel, using an electric motor has been proposed (see, for example, Patent Document 1). By using such a transmission ratio variable device, the turning angle of the wheel with respect to the steering angle of the steering wheel can be changed according to the situation.

JP 2010-215067 A

  When the steering wheel is steered while the vehicle is stopped, that is, when the vehicle is stationary, the driver needs a large force. However, in the technique described in the above-mentioned patent document, since the electric power steering device operates according to the steering torque at the time of stationary, it is necessary to use a large power steering motor to generate the necessary auxiliary force. Occurs. For this reason, it is difficult to reduce the size, cost, or delete the power steering motor.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to realize miniaturization, cost reduction, or deletion of a power steering motor.

  In order to solve the above-described problem, a steering apparatus according to an aspect of the present invention includes a transmission ratio variable mechanism that changes a transmission ratio that is a ratio of a steering angle of a wheel to a steering angle of a steering wheel. The transmission ratio variable mechanism lowers the transmission ratio when the steering wheel is steered at a speed lower than a predetermined vehicle speed, when the steering wheel is increased, compared to a case where the steering wheel is steered at a speed higher than the predetermined vehicle speed. At the time of returning, the transmission ratio is lowered as compared with the time of increasing.

  According to this aspect, the transmission ratio can be reduced and fixed. Further, since the transmission ratio is lowered when the steering wheel is returned compared to when the steering wheel is increased, the wheel can be largely steered by repeating the steering wheel increasing steering and the return steering.

  When the steering wheel is returned at a speed lower than the predetermined vehicle speed, the transmission ratio variable mechanism is configured so that the steering wheel should be positioned to steer at the predetermined vehicle speed or higher to the wheel angle at the start of the return. The transmission ratio may be lowered as compared with the time of increasing until reaching the value.

  According to this aspect, the steering wheel can be easily returned to the normal steering angle without turning the wheel in the reverse direction. For this reason, it is possible to suppress a sense of incongruity when the steering wheel is returned to the normal steering angle at a predetermined vehicle speed or higher.

  The transmission ratio variable mechanism is provided so as to be rotatable at least in a direction to return the steering wheel. When the steering force to the steering wheel is released at a speed lower than the predetermined vehicle speed, the transmission wheel is rotated until the normal steering angle is reached. You may return.

  According to this aspect, the driver can return the steering wheel to the normal steering angle only by releasing the steering wheel. For this reason, it is possible to more appropriately suppress the uncomfortable feeling when the normal steering condition is satisfied and the transmission ratio becomes high.

  According to the present invention, it is possible to reduce the size, reduce the cost, or delete the power steering motor.

(A) And (b) is a figure which shows the structure of the steering apparatus which concerns on this embodiment. (A) is a figure which shows the transmission ratio variable mechanism of a normal transmission ratio state. It is a flowchart which shows the execution procedure of the steering control by the steering apparatus which concerns on this embodiment. It is a flowchart which shows in detail the execution procedure of stationary mode control of S12 in FIG. It is a flowchart which shows the execution procedure of steering control at the time of stationary of S22 in FIG. It is a flowchart which shows the execution procedure of stationary non-steering control of S24 in FIG. (A) is a figure which shows a mode that a wheel is steered gradually. (B) is a figure which shows the steering angle of the steering wheel for implement | achieving the turning angle of the wheel shown to (a) in normal mode. (C) is a figure which shows the steering angle of the steering wheel for implement | achieving the turning angle of the wheel shown to (a). (A) is a diagram showing a main shaft angle θm and a ring gear angle θr with respect to the steering wheel angle θs when the steering wheel is increased in the stationary mode. (B) is a diagram showing a main shaft angle θm and a ring gear angle θr with respect to the steering wheel angle θs when the steering wheel is released from the state of (a).

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

  Fig.1 (a) and FIG.1 (b) are figures which show the structure of the steering apparatus 10 which concerns on this embodiment. FIG. 1A shows a perspective view of the main configuration of the steering device 10, and FIG. 1B schematically shows the configuration of the steering device 10.

  The steering device 10 is a device that steers the wheel 20 in accordance with the steering angle of the steering wheel 12, and includes the steering wheel 12, the steering shaft 14, the main shaft 16, the transmission ratio variable mechanism 18, and A steering mechanism 19 is provided.

  The transmission ratio variable mechanism 18 changes a transmission ratio that is a ratio of the turning angle of the wheel 20 to the steering angle of the steering wheel 12. The transmission ratio variable mechanism 18 includes a sun gear 22, a planetary gear 24, a ring gear 26, a first disk 28, a second disk 30, a shaft 32, a first rotating member 40, a drum 42, a fixing member 44, a first clutch 50, a first clutch 50, 2 clutch 52, second rotating member 54, fixed member 56, third clutch 58, return mechanism 60, and electronic control unit (hereinafter referred to as “ECU”) 100.

  The upper end of the steering shaft 14 is coaxially fixed to the steering wheel 12. The lower end of the steering shaft 14 is coaxially fixed to the sun gear 22. The sun gear 22 is engaged with a plurality of planetary gears 24 having the same shape. Further, a ring gear 26 meshes with the plurality of planetary gears 24 so as to surround the outer periphery thereof. In the present embodiment, four planetary gears 24 are used. Of course, the number of planetary gears 24 is not limited to two.

  In each of the plurality of planetary gears 24, a shaft 32 is coaxially penetrated and fixed. A first disk 28 is disposed above the sun gear 22 so as to be coaxial with the steering shaft 14 and rotatable with respect to the steering shaft 14. The upper ends of each of the plurality of shafts 32 are rotatably supported by the first disk 28. A second disk 30 is disposed below the sun gear 22 so as to be rotatable coaxially with the sun gear 22. The upper ends of each of the plurality of shafts 32 are rotatably supported by the second disk 30.

  The upper end of the main shaft 16 is coaxially fixed to the second disk 30. The lower end of the main shaft 16 is connected to the steering mechanism 19. The steered mechanism 19 converts the rotational motion of the main shaft 16 into the steered motion of the wheel 20 to be steered. Since the structure of the steering mechanism 19 is well-known, the description about the detailed structure is abbreviate | omitted.

  A first rotating member 40 is fixed to the steering shaft 14. A drum 42 is fixed to the ring gear 26. A first clutch 50 is provided between the first rotating member 40 and the drum 42. A fixing member 44 is fixed to the vehicle body. A second clutch 52 is provided between the fixing member 44 and the drum 42. A second rotating member 54 is fixed to the main shaft 16. A fixing member 56 is fixed to the vehicle body. A third clutch 58 is provided between the second rotating member 54 and the fixed member 56.

  When the first clutch 50 is turned on, both the first rotating member 40 and the drum 42 are fixed so as to rotate together. When the first clutch 50 is turned off, the first rotating member 40 and the drum 42 can be relatively rotated. When the second clutch 52 is turned on, both the drum 42 and the fixing member 44 are fixed so as to rotate together. When the first clutch 50 is turned off, the drum 42 and the fixed member 44 are relatively rotatable. When the third clutch 58 is turned on, both the second rotating member 54 and the fixed member 56 are fixed so as to rotate together. When the third clutch 58 is turned off, the second rotating member 54 and the fixed member 56 are relatively rotatable.

  The first clutch 50, the second clutch 52, and the third clutch 58 are each connected to the electric ECU 100. ECU 100 controls on / off of first clutch 50, second clutch 52, and third clutch 58. Note that clutches that can be connected and disconnected by turning on and off, such as the first clutch 50, the second clutch 52, and the third clutch 58, are well known. Omitted.

  A return mechanism 60 is attached to the steering shaft 14. The return mechanism 60 rotates the steering wheel 12 in the return direction. The return mechanism 60 has a motor 62, a motor gear 64, and a gear 66. The gear 66 is fixed by inserting the steering shaft 14. The motor gear 64 is fixed to the motor shaft of the motor 62. The motor gear 64 and the gear 66 are meshed with each other.

  Thus, when the transmission ratio variable mechanism 18 releases the connection between the steering shaft 14 and the wheels 20 and the transmission ratio is set to zero, the steering shaft 14 can be rotated by operating the motor 62.

  In the present embodiment, the ECU 100 controls on / off of the first clutch 50, the second clutch 52, and the third clutch 58, so that any of the normal transmission ratio state, the low transmission ratio state, and the transmission ratio zero state is selected. Let's move to. Since the turning angle of the wheel 20 and the rotation angle of the main shaft 16 are proportional, the ratio of the rotation angle of the main shaft 16 to the steering angle of the steering wheel 12 will be described below as a “transmission ratio”. In the present embodiment, the “steering angle” refers to the rotation angle of the steering wheel 12 from the initial position of the steering wheel 12 that should be positioned when the vehicle goes straight.

  In the normal transmission ratio state, the transmission ratio is set to 1. That is, in the normal transmission ratio state, the main shaft 16 rotates by the same angle as the steering angle of the steering wheel 12. In the low transmission ratio state, the transmission ratio is set to 1/3. Therefore, the main shaft 16 rotates by an angle that is 1/3 of the steering angle of the steering wheel 12. In the transmission ratio zero state, the transmission ratio is set to zero. Accordingly, the connection between the steering shaft 14 and the main shaft 16 is released, and the main shaft 16 does not rotate even when the steering shaft 14 is steered. Hereinafter, the normal transmission ratio state, the low transmission ratio state, and the transmission ratio zero state will be described in detail with reference to FIGS. 2 (a) to 2 (c).

  FIG. 2A is a diagram showing the transmission ratio variable mechanism 18 in the normal transmission ratio state. In the normal transmission ratio state, the ECU 100 turns on the first clutch 50, turns off the second clutch 52, and turns off the third clutch 58. As a result, the steering shaft 14 and the ring gear 26 are fixed via the first rotating member 40 and the drum 42. Since the steering shaft 14 and the sun gear 22 are originally fixed, the plurality of planetary gears 24 meshed with both the sun gear 22 and the ring gear 26 also have the same angle as the steering angle of the steering shaft 14 and the axis of the sun gear 22. Revolve to the center. The main shaft 16 rotates through the shaft 32 and the second disk 30 at the same angle as the revolution angle of the plurality of planetary gears 24. Therefore, the main shaft 16 rotates by the same angle as the steering angle of the steering shaft 14, and the transmission ratio in the normal transmission ratio state is 1.

  FIG. 2B is a diagram showing the transmission ratio variable mechanism 18 in the low transmission ratio state. In the low transmission ratio state, the ECU 100 turns off the first clutch 50, turns on the second clutch 52, and turns off the third clutch 58. As a result, the ring gear 26 is fixed to the vehicle body via the drum 42 and the fixing member 44, and thus cannot be rotated. For this reason, when the steering shaft 14 rotates, the sun gear 22 rotates but the ring gear 26 does not rotate, and a plurality of planetary gears 24 between the sun gear 22 and the ring gear 26 rotate and revolve around the sun gear 22. To do.

  In the present embodiment, when the ring gear 26 is fixed, the specifications of the respective gears are set so that the plurality of planetary gears 24 makes one third rotation while the sun gear 22 makes one rotation. As described above, the revolution angle of the plurality of planetary gears 24 becomes the rotation angle of the main shaft 16. For this reason, the main shaft 16 rotates by 1/3 of the steering angle of the steering shaft 14, and the transmission ratio in the low transmission ratio state becomes 1/3.

  FIG. 2C is a diagram showing the transmission ratio variable mechanism 18 in a transmission ratio zero state. In the transmission ratio zero state, the ECU 100 turns off the first clutch 50, turns off the second clutch 52, and turns on the third clutch 58. As a result, the main shaft 16 is fixed to the vehicle main body via the second rotating member 54 and the fixing member 56 and cannot rotate. Therefore, the plurality of planetary gears 24 can rotate but cannot revolve. On the other hand, the ring gear 26 is not fixed to the vehicle body or the steering shaft 14. For this reason, when the steering shaft 14 is rotated, the plurality of planetary gears 24 rotate without revolving, so that the ring gear 26 idles in the direction opposite to the rotation direction of the sun gear 22. Therefore, the rotation angle of the main shaft 16 is zero with respect to the steering angle of the steering shaft 14, and the transmission ratio in the transmission ratio zero state is zero.

  Note that the transmission ratio variable mechanism 18 may be in a second low transmission ratio state in which the transmission ratio is lowered when the steering wheel 12 is returned, compared to when the steering wheel 12 is increased, instead of the transmission ratio zero state. For example, a second planetary gear mechanism is provided in the transmission ratio variable mechanism 18 for the second low transmission ratio state. In the second low transmission ratio state, the second planetary gear mechanism is used to increase the steering wheel 12 when the steering wheel 12 is returned. You may reduce a transmission ratio compared with the case.

  Here, at the time of stationary, if the transmission ratio is high as in the normal transmission ratio state, the driver has a large force to steer the steering wheel 12 unless the steering force is assisted using an electric power steering device or the like. Necessary. On the other hand, it is also possible to use a transmission ratio variable device to reduce the transmission ratio at the time of stationary. However, when the transmission ratio is lowered, it is difficult to steer the wheel 20 greatly even if the steering wheel 12 is steered to the limit steering angle.

  For this reason, in this embodiment, the transmission ratio variable mechanism 18 has a transmission ratio when the steering wheel 12 is steered at a speed lower than the predetermined vehicle speed, compared with a case where the steering wheel 12 is steered at a speed higher than the predetermined vehicle speed when the steering wheel 12 is increased. The transmission ratio is lowered when the steering wheel 12 is returned compared to when the steering wheel 12 is increased. Specifically, the transmission ratio variable mechanism 18 determines whether or not a predetermined on-off condition that should be satisfied in order to determine that the steering wheel 12 has been fixed is satisfied, or to determine that the steering wheel 12 has been steered while the vehicle is traveling. It is determined whether a predetermined normal steering condition to be satisfied is satisfied. In this embodiment, it is determined that the stationary condition is satisfied when the speed is less than the predetermined speed, and the normal steering condition is determined when the speed is equal to or higher than the predetermined speed. Of course, the stationary condition and the normal steering condition are not limited to this. When the stationary condition is satisfied, the transmission ratio variable mechanism 18 lowers the transmission ratio when the steering wheel 12 is increased more than when the normal steering condition is satisfied, and the steering wheel 12 and the wheel 20 when the steering wheel 12 is returned. And the transmission ratio is made zero. Hereinafter, this transmission ratio control will be described in detail with reference to the flowchart.

  FIG. 3 is a flowchart showing a procedure for performing steering control by the steering apparatus 10 according to the present embodiment. A vehicle speed sensor (not shown) that detects the vehicle speed by detecting the rotational speed of the wheel 20 is provided in the vicinity of the wheel 20 of the vehicle on which the steering device 10 is mounted. The ECU 100 acquires the detection result of the vehicle speed sensor, and determines whether or not the vehicle is stopped by determining whether or not the vehicle speed is zero or less than a predetermined speed at which the vehicle is considered to be stopped (S10).

  When the vehicle is stopped (Y in S10), the ECU 100 determines that the stationary condition is satisfied, and executes the stationary mode control. When the vehicle is traveling (N in S10), the ECU 100 determines that the normal steering condition is satisfied, and executes normal mode control. In this normal mode control, the ECU 100 turns on the first clutch 50, turns off the second clutch 52, and turns off the third clutch 58 to place the transmission ratio variable mechanism 18 in the normal transmission ratio state.

  FIG. 4 is a flowchart showing in detail the execution procedure of the stationary mode control in S12 in FIG. The steering shaft 14 is provided with a steering angle sensor (not shown) that detects the steering angle of the steering shaft 14. ECU100 acquires the detection result of a rudder angle sensor. The ECU 100 determines whether or not the steering wheel 12 is steered using the detection result of the steering angle sensor (S20). When the steering wheel 12 is being steered (Y in S20), the ECU 100 executes steering control at the time of stationary (S22). When the vehicle is not steered (N in S20), the ECU 100 executes the non-steering control at the time of stationary (S24).

  FIG. 5 is a flowchart showing an execution procedure of the stationary steering control in S22 in FIG. In the stationary steering control, the ECU 100 determines whether the steering wheel 12 has been turned up or returned using the detection result of the steering angle sensor (S50). When the steering wheel 12 is increased (Y in S50), the ECU 100 turns off the first clutch 50, turns on the second clutch 52, turns off the third clutch 58, and sets the transmission ratio variable mechanism 18 in the low transmission ratio state. (S52).

  Hereinafter, the steering angle of the steering wheel 12 corresponding to the turning angle of the wheel 20 when the steering wheel 12 is steered in the normal transmission ratio state is referred to as a normal steering angle. When the steering wheel 12 is returned (N in S50), the ECU 100 determines whether or not the steering angle of the steering wheel 12 at that time is equal to or greater than the normal steering angle (S54).

  When the steering angle is equal to or greater than the normal steering angle (Y in S54), the ECU 100 turns off the first clutch 50, turns off the second clutch 52, and turns on the third clutch 58 to bring the transmission ratio variable mechanism 18 into the transmission ratio zero state ( S56). Thus, when the steering wheel 12 is returned when the stationary condition is satisfied, the transmission ratio variable mechanism 18 is steered when the normal steering condition is satisfied up to the angle of the wheel 20 when the steering wheel 12 starts to return. The transmission ratio is set to zero until the normal steering angle at which the steering wheel 12 should be positioned is reached. Accordingly, the driver can increase the steering wheel 12 in the low transmission ratio state and return the steering wheel 12 in the transmission ratio zero state. For this reason, it becomes possible to steer the steering wheel 12 with a steering force lower than that in the normal transmission ratio state by repeating the increase and the return.

  When it is not the normal steering angle or more (N in S54), the ECU 100 turns off the first clutch 50, turns on the second clutch 52, turns off the third clutch 58, and sets the transmission ratio variable mechanism 18 to the low transmission ratio state ( S52). Therefore, when returning the steering wheel 12 to an angle smaller than the normal steering angle, the transmission ratio is not zero, but the transmission ratio is low, so that the turning angle of the wheel 20 can be returned to the low transmission ratio.

  FIG. 6 is a flowchart showing the execution procedure of the non-steering control at the time of stationary in S24 in FIG. The ECU 100 determines whether or not the steering angle of the steering wheel 12 at that time is larger than the normal steering angle (S80).

  If it is larger than the normal steering angle (Y in S80), the ECU 100 turns off the first clutch 50, turns off the second clutch 52, and turns on the third clutch 58 to bring the transmission ratio variable mechanism 18 into the transmission ratio zero state. (S82). Next, the ECU 100 operates the return mechanism 60 to return the steering wheel 12 to the normal steering angle (S84). Thus, when the steering force to the steering wheel 12 is released during the stationary mode, the ECU 100 returns the steering wheel 12 until the normal steering angle is reached. Thereby, when the vehicle starts to travel, it is possible to smoothly shift to the normal mode. If the steering angle of the steering wheel 12 has already become the normal steering angle (N in S80), the ECU 100 skips S82 and S84 and avoids the returning operation of the steering wheel 12.

  Fig.7 (a) is a figure which shows a mode that the wheel 20 is steered gradually. FIG. 7B is a diagram showing the steering angle of the steering wheel 12 for realizing the turning angle of the wheel 20 shown in FIG. 7A during the normal mode. As described above, during the normal mode, the wheel 20 can be steered without greatly steering the steering wheel 12.

  FIG.7 (c) is a figure which shows the steering angle of the steering wheel 12 for implement | achieving the turning angle of the wheel 20 shown to Fig.7 (a). As described above, during the stationary mode, the steering wheel 12 needs to be steered greatly in order to steer the wheel 20 as in the normal mode. However, the steering wheel 12 can be steered with a smaller steering force. Further, the driver simply releases the steering wheel 12 after steering the steering wheel 12 and automatically returns the steering wheel 12 to the normal steering angle that is the steering angle of the steering wheel 12 that should be positioned in the normal mode. Can do. For this reason, the frequency at which the steering wheel 12 is positioned at the normal steering angle can be increased, and even when the vehicle starts traveling, the mode can be smoothly shifted to the normal mode.

  FIG. 8A is a diagram showing the main shaft angle θm and the ring gear angle θr with respect to the steering wheel angle θs when the steering wheel 12 is increased in the stationary mode. 8A and 8B, θs represents a steering wheel angle, θm represents a main shaft angle, and θr represents a ring gear angle. The steering wheel angle θs refers to the steering angle of the steering wheel 12 from the initial position when the vehicle is traveling straight. The main shaft angle θm refers to the rotation angle of the main shaft 16 from the initial position when the vehicle is traveling straight. Further, it means the rotation angle of the ring gear 26 from the initial position when the vehicle goes straight.

  A line L1 indicates the relationship between the steering wheel angle θs and the main shaft angle θm in the normal transmission ratio state. Line L2 shows the relationship between the steering wheel angle θs and the main shaft angle θm in the low transmission ratio state. A line L3 indicates the relationship between the steering wheel angle θs and the ring gear angle θr in the normal transmission ratio state.

  As shown in FIG. 8A, while the steering wheel 12 is steered and the steering wheel angle θs increases to the first steering angle θs1 that is equal to or less than the limit steering angle, the relationship A1 between the steering wheel angle θs and the main shaft angle θm. Moves along line L2. Therefore, the main shaft angle θm rotates by an angle of 1/3 compared to L1 indicating that the normal mode is being performed, and the driver can steer the steering wheel 12 with a correspondingly small steering force. On the other hand, since the ring gear 26 is locked while the steering wheel angle θs increases to the first steering angle θs1 that is equal to or less than the limit steering angle, the relationship B1 between the steering wheel angle θs and the ring gear angle θr is expressed by the ring gear angle. It moves parallel to the horizontal axis while θr remains zero.

  FIG. 8B is a diagram showing the main shaft angle θm and the ring gear angle θr with respect to the steering wheel angle θs when the steering wheel 12 is released from the state of FIG.

  When the steering wheel 12 is released after the steering wheel angle θs has increased to the first steering angle θs1, the return mechanism 60 rotates the steering wheel 12 in the returning direction, so that the steering wheel angle θs decreases. At this time, since the main shaft 16 is locked and the main shaft angle θm does not change, the relationship A2 between the steering wheel angle θs and the main shaft angle θm is parallel to the horizontal axis. Since the steering wheel angle θs reaches the normal steering angle when A2 reaches the line L1, the return operation of the steering wheel 12 by the return mechanism 60 stops at the second steering angle θs2 at this time.

  When the steering wheel 12 is released, the transmission ratio becomes zero and the lock of the ring gear 26 is released. Therefore, the relationship B2 between the steering wheel angle θs and the ring gear angle θr is such that the steering wheel angle θs is the second steering. When the angle θs2 is reached, it changes linearly so as to intersect the line L3. Further, when it is desired to steer the wheel 20, the driver repeats the operation of releasing the steering wheel 12 and returning it to the normal steering angle with the steering wheel 12 after the steering wheel 12 is increased, thereby further turning the wheel 20 to the steering angle. Can be made.

  The present invention is not limited to the above-described embodiment, and an appropriate combination of the elements of this embodiment is also effective as an embodiment of the present invention. Various modifications such as various design changes can be added to the present embodiment based on the knowledge of those skilled in the art, and the embodiments with such modifications can be included in the scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 Steering device, 12 Steering wheel, 14 Steering shaft, 16 Main shaft, 18 Transmission ratio variable mechanism, 19 Steering mechanism, 20 Wheel, 22 Sun gear, 24 Planetary gear, 26 Ring gear, 28 1st disk, 30 2nd disk Disc, 32 shaft, 40 first rotating member, 42 drum, 44 fixing member, 50 first clutch, 52 second clutch, 54 second rotating member, 56 fixing member, 58 third clutch, 100 ECU.

  The present invention can be used for a steering device, and in particular, can be used for a steering device provided with a transmission ratio variable mechanism.

Claims (3)

With a transmission ratio variable mechanism that changes the transmission ratio, which is the ratio of the steering angle of the wheel to the steering angle of the steering wheel,
The transmission ratio variable mechanism lowers the transmission ratio when the steering wheel is steered at a speed lower than a predetermined vehicle speed, when the steering wheel is increased, compared to a case where the steering wheel is steered at a speed higher than the predetermined vehicle speed. A steering device characterized in that the transmission ratio is lowered when returning the gear as compared with when increasing.   When the steering wheel is returned at a speed lower than the predetermined vehicle speed, the transmission ratio variable mechanism is configured so that the steering wheel should be positioned to steer at the predetermined vehicle speed or higher up to the wheel angle at the time of starting the return. The steered device according to claim 1, wherein the transmission ratio is lowered as compared with the time of increasing until reaching the value.   The transmission ratio variable mechanism is provided so as to be rotatable at least in a direction to return the steering wheel. When the steering force to the steering wheel is released at a speed lower than the predetermined vehicle speed, the transmission wheel is rotated until the normal steering angle is reached. The steering apparatus according to claim 2, wherein the steering apparatus is returned.

Images