JP5557097B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus.

  A vehicle steering apparatus comprising a transmission ratio variable mechanism capable of changing a rotation transmission ratio between an input shaft and an output shaft between an input shaft connected to a steering member and an output shaft connected to a steering mechanism. Is known (see, for example, Patent Documents 1 to 3). The transmission ratio variable mechanism is composed of a planetary gear mechanism, a wave gear mechanism, etc., and the electric motor (transmission ratio control motor) rotates the carrier of the planetary gear mechanism and the wave generator of the wave gear mechanism, thereby rotating the rotation transmission ratio. Can be changed. In addition, a vehicle steering apparatus including a transmission ratio variable mechanism includes various rotation angle sensors such as a resolver, and an appropriate rotation transmission ratio is controlled by using detection results of these rotation angle sensors. It is like that.

JP 2006-159991 A Japanese Patent Laying-Open No. 2005-212616 JP 2006-10336 A

In a vehicle steering apparatus provided with a transmission ratio variable mechanism, the reaction force transmitted to the steering member changes due to the operation of the transmission ratio variable mechanism. Therefore, a reaction force compensation motor for compensating for the change in the reaction force may be provided. is there. In this case, in addition to the resolver that detects the position of the rotor of the transmission ratio control motor, a resolver that detects the position of the rotor of the reaction force compensation motor is provided.
If an abnormality occurs in these resolvers, it becomes impossible to correctly control the rotation transmission ratio and compensate the reaction force. Therefore, when an abnormality occurs in the resolver, it is necessary to take measures such as mechanically fixing the rotation transmission ratio. As described above, it is necessary to reliably detect an abnormality of a rotational angle sensor such as a resolver so that a measure corresponding to the abnormality of the resolver can be taken.

For example, it is conceivable to provide a dedicated sensor on the output shaft or the like for detecting an abnormality of the resolver for the transmission ratio control motor. However, it is not preferable from the viewpoint of manufacturing cost to further provide a dedicated sensor for detecting the abnormality of the resolver.
The present invention has been made under such a background, and an object of the present invention is to provide a vehicle steering apparatus that can detect an abnormality of a sensor more reliably and is preferable from the viewpoint of manufacturing cost.

In order to achieve the above object, the present invention provides an input shaft (18) that rotates in response to steering of the steering member (2) and an output shaft (19) that rotates in conjunction with the operation of the steering mechanism (9). A transmission ratio variable mechanism (13) interposed between the input shaft and the output shaft, and a transmission ratio control motor (14) for changing the transmission ratio of the transmission ratio variable mechanism; A first sensor (31) for detecting a rotational position (θvgr) of the transmission ratio control motor; and a reaction force compensation motor (15) for compensating for a steering reaction force of the steering member due to the operation of the transmission ratio variable mechanism. A second sensor (32) for detecting a rotational position (θreact) of the reaction force compensation motor, and a control unit (37) for controlling the transmission ratio control motor and the reaction force compensation motor, the control unit Is the first sensor or the second sensor? A first determination unit (49) for determining whether or not there is an abnormality of the predetermined sensor, wherein the first determination unit is controlled by the transmission ratio control motor or the reaction force compensation motor corresponding to the predetermined sensor. When the first target angle (δ1) is rotated in the predetermined rotation direction by the open loop control by the unit, the difference between the change amount (Δθvgr1) of the detection value of the predetermined sensor and the first target angle is the first reference When the value (θ1) is exceeded, it is determined that an abnormality has occurred in the predetermined sensor, and the control unit determines whether the predetermined sensor has an abnormality in the first determination unit, A function of rotating the transmission ratio control motor or the reaction force compensation motor corresponding to a predetermined sensor in a direction opposite to the predetermined rotation direction by a first return angle equal to the first target angle by open loop control. When the first determination unit determines that there is no abnormality in the predetermined sensor, the transmission ratio control motor or the reaction force compensation motor corresponding to the predetermined sensor is moved in a direction opposite to the predetermined rotation direction. In addition , the vehicle steering apparatus (1) has a function of rotating at a rotation angle corresponding to the change amount of the detection value of the predetermined sensor by feedback control using the predetermined sensor. (Claim 1).

According to the present invention, the transmission ratio can be changed by driving the transmission ratio variable mechanism motor. Further, the reaction force acting on the steering member can be compensated by driving the reaction force compensation motor.
Also, consider a case where a transmission ratio control motor or reaction force compensation motor corresponding to a predetermined sensor is rotated by a control unit by a first target angle in a predetermined rotation direction. In this case, if there is no abnormality in the predetermined sensor, the change amount of the predetermined sensor becomes substantially the same value as the first target angle. On the other hand, if there is an abnormality in the predetermined sensor due to the rotor of the predetermined sensor being removed from the member to be fixed, etc., the amount of change in the detection value of the predetermined sensor is larger than the first target angle. It will shift. Therefore, when the difference between the change amount of the detection value of the predetermined sensor and the first target angle exceeds the first reference value, it can be determined that an abnormality has occurred in the predetermined sensor. Thereby, abnormality of a predetermined sensor can be detected more reliably. In addition, since a dedicated sensor for detecting an abnormality of a predetermined sensor is not provided, the number of parts can be reduced, which is preferable from the viewpoint of manufacturing cost.

  For example, when the predetermined sensor is the first sensor, an abnormality of the first sensor can be reliably detected. Thereby, the abnormality of the control of the transmission ratio due to the abnormality of the first sensor can be suppressed. For example, when the first sensor includes a sensor rotor that rotates integrally with the motor rotor of the transmission ratio control motor, the sensor rotor may fall off from the motor rotor or the like due to vibration or aging deterioration during traveling on a rough road of the vehicle. At this time, if the output of the first sensor is simply interrupted, an abnormality of the first sensor is detected, so that even if the sensor rotor falls off, an output signal from the first sensor is issued. Abnormality cannot be detected. Under such an abnormality, the rotational position of the transmission ratio control motor cannot be detected by the first sensor. As a result, although the rotational position of the transmission ratio control motor cannot be detected by the first sensor, a control current continues to flow through the transmission ratio control motor to reach the target rotational position. Cause failure.

  On the other hand, in the present invention, the first target angle which is a command value from the control unit to the transmission ratio control motor is not simply determined whether or not the detection value of the first sensor exceeds the threshold value. And the amount of change in the detection value of the first sensor, it can be determined whether or not an abnormality has occurred in the first sensor. Therefore, the abnormality of the first sensor can be detected more reliably. For this reason, the rotational position of the transmission ratio control motor can be detected with high reliability by the first sensor. As a result, when the transmission ratio control motor reaches the target rotation position, the first sensor detects that fact, and the feedback control that the control current to the transmission ratio control motor stops can be reliably maintained. Therefore, current does not continue to flow through the transmission ratio control motor indefinitely. Thereby, failure of the transmission ratio control motor can be suppressed, and appropriate transmission ratio control can be realized.

  The reaction force compensation motor is connected to the input shaft, and the transmission ratio variable mechanism is an input sun gear connected to the input shaft, and an output sun gear that is arranged coaxially with the input sun gear and connected to the output shaft. A planetary gear that meshes with both the input sun gear and the output sun gear, and a carrier that can revolve around the input sun gear and that can rotate about the central axis of the planetary gear. The rotor of the control motor may be coupled to the carrier so as to be integrally rotatable.

In this case, the output of the reaction force compensation motor is transmitted to the steering member via the input shaft, and the reaction force of the steering member is compensated. The output of the transmission ratio control motor is transmitted to the output shaft via the carrier and the planetary gear, and the transmission ratio is controlled.
Further, the prior SL controller, after determining the presence or absence of abnormality of the predetermined sensor by the first determination unit, the transmission ratio control motor or the reaction-force compensation motor corresponding to the predetermined sensor, said predetermined The function of rotating the first return angle equal to the first target angle by open loop control in a direction opposite to the rotation direction, and the predetermined determination unit when the first determination unit determines that there is no abnormality The transmission ratio control motor or the reaction force compensation motor corresponding to the sensor of the sensor is fed back in a direction opposite to the predetermined rotation direction by feedback control using the sensor to detect the detected value of the sensor. And a function of rotating at a rotation angle corresponding to the amount of change .

  In this case, since the corresponding transmission ratio control motor or the reaction force compensation motor is rotated when determining whether or not there is an abnormality in the predetermined sensor, the steered wheels also operate in conjunction with each other. Therefore, after the presence / absence of abnormality of the predetermined sensor is determined, the rotational position of the corresponding transmission ratio control motor or reaction force compensation motor is returned to the position before the determination of the presence / absence of abnormality of the predetermined sensor. I have to. Thereby, when the presence or absence of abnormality of a predetermined sensor is determined, it is possible to suppress the driver from feeling uncomfortable that the position of the steered wheels that are not directly related changes.

Further, in the present invention, further comprising a torque sensor (30) for detecting a torque acting on the steering member, and when the control unit determines that the predetermined sensor is normal in the first determination unit, The second determination unit includes a second determination unit (50) that determines whether the torque sensor is abnormal. The second determination unit rotates the transmission ratio control motor by a second target angle (δ2) in a predetermined rotation direction by the control unit. In this case, when the difference between the predetermined reference torque (k · δ2) and the detected value (T0 ′) of the torque sensor exceeds the second reference value (T2), an abnormality occurs in the torque sensor. (Claim 2 ).

  In this case, torque is applied to the input shaft or the like by driving the transmission ratio control motor, and this torque is detected by the torque sensor. If an abnormality occurs in the torque sensor, the detected value of the torque sensor does not change in response to the torque change, even though the input shaft or the like is loaded with torque by driving the transmission ratio control motor. Therefore, the abnormality of the torque sensor can be detected more reliably.

The predetermined reference torque may be a value obtained by multiplying the second target angle by a predetermined coefficient. In this case, a value directly related to the second target angle can be used as the reference torque.
Further, in the present invention, the control unit, the after determining the presence or absence of an abnormality in the torque sensor in the second judging unit, said transmission ratio control motor, the second target in the opposite direction to the predetermined rotational direction a function of the second return angle Dokai rotation equal to the angle, if it is determined that there is no abnormality in the torque sensor in the second judging unit, said transmission ratio control motor, in a direction opposite to the predetermined rotational direction A function of rotating the transmission ratio control motor by a rotation angle corresponding to a change amount of a detection value of the predetermined sensor detected when the transmission ratio control motor is rotated by the second target rotation angle by feedback control using the predetermined sensor. with the door (claim 3).

  In this case, since the transmission ratio control motor is rotated when determining whether there is an abnormality in the torque sensor, the steered wheels also operate in conjunction with each other. Therefore, after the presence / absence of abnormality of the torque sensor is determined, the rotational position of the transmission ratio control motor is returned to the position before determining the presence / absence of abnormality of the torque sensor. Thereby, if the presence or absence of abnormality of a torque sensor is determined, it can suppress giving a driver the uncomfortable feeling that the position of the steered wheel which is not directly related will change.

In the present invention, a lock mechanism (25) that can lock the rotation of the transmission ratio control motor is further provided, and the control unit drives the lock mechanism when it is determined that an abnormality has occurred in the sensor. As a result, the rotation of the transmission ratio control motor may be locked and the drive of the transmission ratio control motor may be stopped (claim 4 ).
In this case, in a failure state where the transmission ratio control motor and the reaction force compensation motor cannot be accurately controlled, the transmission ratio can be mechanically fixed by the lock mechanism by the lock mechanism. Thereby, the state in which the steering mechanism can be operated by the steering member can be maintained. In addition, since the drive of the transmission ratio control motor is stopped, it is possible to prevent the drive ratio from continuing to flow through the transmission ratio control motor and failing.

  In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles concerning one embodiment of the present invention. It is a partial cross section figure which shows schematic structure of a transmission ratio variable mechanism. (A) is sectional drawing of the principal part of a locking mechanism, and shows the state where the locking mechanism has not locked the carrier, and (B) shows the state where the locking mechanism has locked the carrier. . It is a flowchart for demonstrating the flow of control which sets abnormality determination mode. It is a flowchart for demonstrating the flow of control of 1st abnormality determination mode. (A)-(e) is a schematic diagram for demonstrating the operation | movement of a steered wheel, respectively, when performing abnormality determination mode. It is a flowchart for demonstrating the flow of control of 2nd abnormality determination mode. It is a graph for demonstrating the relationship between the rotation angle of a transmission ratio control motor, and the torque which acts on an input shaft. It is a flowchart for demonstrating the flow of control in fail mode. It is a schematic diagram of the principal part of another embodiment of this invention.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus according to an embodiment of the present invention.
Referring to FIG. 1, a vehicle steering apparatus 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, an intermediate shaft 5 A pinion shaft 7 connected to the shaft 5 through a universal joint 6 and a rack 8a meshing with the pinion 7a provided in the vicinity of the end of the pinion shaft 7 and extending in the left-right direction of a vehicle such as an automobile As a rack shaft 8. The pinion shaft 7 and the rack shaft 8 constitute a turning mechanism 9 including a rack and pinion mechanism.

The rack shaft 8 is supported in a housing (not shown) fixed to the vehicle body through a plurality of bearings (not shown) so as to be capable of linear reciprocation along the axial direction X1. A tie rod 10 is coupled to each end of the rack shaft 8. Each tie rod 10 is connected to a corresponding steered wheel 11 via a corresponding knuckle arm (not shown).
When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion in the axial direction X1 of the rack shaft 8 by the pinion 7a and the rack 8a. Thereby, the turning of the steered wheel 11 is achieved.

  Further, the vehicle steering apparatus 1 changes the ratio (transmission ratio) of the steering angle of the steered wheels 11 to the steering angle of the steering member 2 and the steering assist mechanism 12 for applying a steering assist force to the steering mechanism 9. And a transmission ratio variable mechanism 13 capable of performing the same. The transmission ratio variable mechanism 13 is provided with a transmission ratio control motor 14 as a predetermined motor including a brushless motor capable of changing the transmission ratio. Further, the transmission ratio variable mechanism 13 is provided with a reaction force compensation motor 15 including a brushless motor that can apply a steering reaction force to the steering member 2.

The steering shaft 3 is disposed between the steering member 2 and the transmission ratio variable mechanism 13, and is disposed between the input shaft 18 that rotates according to the steering of the steering member 2, and the transmission ratio variable mechanism 13 and the intermediate shaft 5. And an output shaft 19 that rotates in conjunction with the operation of the steering mechanism 9.
The input shaft 18 includes a first shaft 18a that is coupled to the steering member 2 so as to be integrally rotatable, and a second shaft 18b that is coupled to the first shaft 18a via a torsion bar 20. The relative rotation amount of the first shaft 18a and the second shaft 18b via the torsion bar 20 is small, and it can be considered that the first shaft 18a and the second shaft 18b are substantially rotating integrally.

  The steering assist mechanism 12 includes a steering assist motor 21 formed of a brushless motor, and a speed reduction mechanism 22 that decelerates the output rotation of the steering assist motor 21. The speed reduction mechanism 22 is, for example, a worm speed reduction mechanism, and a worm shaft 23 that is connected to the rotor 21a of the steering assist motor 21 so as to be integrally rotatable, and a worm wheel that is connected to the output shaft 19 so as to be integrally rotatable and meshes with the worm shaft 23. 24.

The steering assist motor 21 is connected to the steering mechanism 9 through the speed reduction mechanism 22, the output shaft 19 and the intermediate shaft 5 so that power can be transmitted. The output of the steering assist motor 21 is transmitted to the output shaft 19 via the speed reduction mechanism 22 to assist the driver's steering.
The vehicle steering apparatus 1 includes a lock mechanism 25 that can lock the rotation of the transmission ratio control motor 14.

Further, the vehicle steering apparatus 1 includes a torque sensor 30, a first resolver 31 as a first sensor, a second resolver 32 as a second sensor, a third resolver 33 as a third sensor, and a transmission ratio. A first current sensor 34 that detects a current of the control motor 14, a second current sensor 35 that detects a current of the reaction force compensation motor 15, and a traveling state sensor 36 are provided.
The torque sensor 30 is disposed adjacent to the torsion bar 20, and is loaded on the steering member 2 by detecting the relative rotation amount between the first shaft 18a and the second shaft 18b accompanying the twist of the torsion bar 20. The steering torque is detected.

The first resolver 31 is a resolver that detects a rotational position of a rotor 14a, which will be described later, of the transmission ratio control motor 14, and is disposed adjacent to the transmission ratio control motor 14 as a predetermined sensor. The transmission ratio control motor 14 is driven and controlled by feedback control using the detected value θvgr of the first resolver 31.
The second resolver 32 is a resolver that detects a rotational position of a rotor 15 a described later of the reaction force compensation motor 15, and is disposed adjacent to the reaction force compensation motor 15. The reaction force compensation motor 15 is driven and controlled by feedback control using the detection value θreact of the second resolver 32. The reaction force compensation motor 15 is a motor for compensating for the steering reaction force (change in the steering reaction force) of the steering member 2 due to the operation of the transmission ratio variable mechanism 13.

The third resolver 33 is a resolver that detects the rotational position of the rotor 21 a of the steering assist motor 21, and is provided in the steering assist motor 21. The steering assist motor 21 is driven and controlled by feedback control using the detected value θeps of the third resolver 33.
The traveling state sensor 36 is a sensor that detects a traveling state of the vehicle (a vehicle traveling state related to the control of the vehicle steering device 1 such as a vehicle speed, a steering angle, and a yaw rate of the vehicle), and includes a plurality of sensors. ing.

The vehicle steering apparatus 1 includes a control unit 37. The control unit 37 controls the steering by controlling the operations of the transmission ratio control motor 14, the reaction force compensation motor 15, and the lock mechanism 25, and the steering assist control that controls the operation of the steering assist motor 21. Part 39.
The steering control unit 38 and the steering assist control unit 39 are each configured by an electronic control unit (ECU), and are connected to each other via a vehicle-mounted network 40 so that signals can be transmitted to each other.

A torque sensor 30, a first resolver 31, a second resolver 32, a third resolver 33, a first current sensor 34, a second current sensor 35, and a traveling state sensor 36 are connected to the steering control unit 38, respectively. Detection signals from the sensors 30 to 36 are input to the steering control unit 38.
The steering control unit 38 is connected to the transmission ratio control motor 14 via a driver 41 and is connected to the reaction force compensation motor 15 via a driver 42. Further, the steering control unit 38 of the control unit 37 is connected to the lock mechanism 25, the steering lock device 26, a warning lamp 44 and a speaker 45 serving as notification means.

The steering control unit 38 is a function processing unit that is realized by software by executing a predetermined program, and includes a transmission ratio control unit 46, a reaction force control unit 47, a mode setting unit 48, and a first determination unit 49. And a second determination unit 50 and a counter 51.
The transmission ratio control unit 46 controls the drive of the transmission ratio control motor 14 in order to control the transmission ratio. The reaction force control unit 47 controls the driving of the reaction force compensation motor 15 in order to control the reaction force applied to the steering member 2. The mode setting unit 48 includes a main mode for controlling driving of the transmission ratio control motor 14, the reaction force compensation motor 15 and the steering assist motor 21, an abnormality determination mode for determining abnormality of the first resolver 31 and the torque sensor 30, and a failure. The mode is set alternatively.

  The vehicle steering apparatus 1 includes a warning lamp 44 and a speaker 45 as notification means. The warning lamp 44 and the speaker 45 are connected to the steering control unit 38. In the fail mode, the warning lamp 44 is lit and the speaker 45 emits a warning sound. Thereby, it is possible to notify the driver of the failure state. The steering assist control unit 39 is connected to the steering assist motor 21 via a driver 43.

  The steering lock device 26 is a so-called key lock device provided for restricting the rotation of the input shaft 18. The vehicle is stolen by restricting the rotation of the steering member 2 and the input shaft 18 when the vehicle is parked. It has a function to suppress. The steering lock device 26 is a solenoid, for example, and includes a housing 26a and a rod 26b. The rod 26 b protrudes from the housing 26 a and can be engaged with the first shaft 18 a of the input shaft 18. Thereby, rotation of the 1st axis | shaft 18a can be controlled. Further, when the rod 26b is retracted in the housing 26a, the rod 26b is not engaged with the first shaft 18a and does not restrict the rotation of the first shaft 18a. The steering lock device 26 is connected to the steering control unit 38. The steering control unit 38 controls engagement / disengagement between the rod 26b and the first shaft 18a.

FIG. 2 is a partial cross-sectional view showing a schematic configuration of the transmission ratio variable mechanism 13. As shown in FIG. 2, the second shaft 18 b and the output shaft 19 of the input shaft 18 are arranged coaxially with their tips opposed to each other.
The transmission ratio variable mechanism 13 can change the transmission ratio between the second shaft 18 b of the input shaft 18 and the output shaft 19. The transmission ratio variable mechanism 13 is accommodated in a housing 53 having a cylindrical shape as a whole.

  The transmission ratio variable mechanism 13 includes an input sun gear 54 that can rotate integrally with the second shaft 18 b of the input shaft 18, and an output sun gear 55 that is disposed coaxially with the input sun gear 54 and can rotate with the output shaft 19. A planetary gear 56 that meshes with each of the sun gears 54, 55, and a carrier 57 that supports the planetary gear 56 so as to be capable of rotating about the central axis L2 of the planetary gear 56 and revolving around the central axis L1 of the sun gears 54, 55. , Including.

  The planetary gear 56 is for associating the input sun gear 54 and the output sun gear 55 with each other, and a plurality (two in this embodiment) are arranged around the central axis L1. The input sun gear 54, the output sun gear 55, and the planetary gear 56 are designed so that the rotation transmission ratio between the input sun gear 54 and the output sun gear 55 becomes 1, for example, when the rotation of the carrier 57 is locked.

  The carrier 57 is formed in a cylindrical shape, and the output shaft 19 is inserted therethrough. The carrier 57 can rotate around the central axis L1 of each sun gear 54, 55. The carrier 57 is supported by the housing 53 via a first bearing 58, and supports a first portion 57a that supports one end of the support shaft 56a of each planetary gear 56, and a second portion 57b that supports the other end of the support shaft 56a. And a third portion 57c extending from the second portion 57b toward the speed reduction mechanism 22 and supported by the housing 53 via a second bearing 59.

  The transmission ratio control motor 14 is disposed so as to surround the second portion 57 b of the carrier 57. The transmission ratio control motor 14 includes a rotor 14 a that is coupled to the outer periphery of the second portion 57 b so as to be integrally rotatable, and a stator 14 b that surrounds the rotor 14 a and is fixed to the housing 53. By driving the transmission ratio control motor 14, the carrier 57 rotates around the central axis L1.

  In relation to the transmission ratio control motor 14, a first resolver 31 is arranged. The first resolver 31 includes a rotor 31 a that is coupled to the outer periphery of the third portion 57 c of the carrier 57 so as to be integrally rotatable, and a stator 31 b that surrounds the rotor 31 a and is fixed to the housing 53. Since both the rotor 14 a of the transmission ratio control motor 14 and the rotor 31 a of the first resolver 31 are connected to the carrier 57, the first resolver 31 can rotate the rotation position (rotation angle) of the carrier 57 and the transmission ratio control motor 14. It is possible to detect the rotational position of the rotor 14a.

A reaction force compensation motor 15 is disposed on the input shaft 18 side (right side in FIG. 2) with respect to the transmission ratio control motor 14. The reaction force compensation motor 15 includes a rotor 15 a connected to the outer periphery of the second shaft 18 b of the input shaft 18, and a stator 15 b that surrounds the rotor 15 a and is fixed to the housing 53.
A second resolver 32 is disposed adjacent to the reaction force compensation motor 15. The second resolver 32 includes a rotor 32 a connected to the outer periphery of the second shaft 18 b and a stator 32 b that surrounds the rotor 32 a and is fixed to the housing 53. By connecting both the rotor 15a of the reaction force compensation motor 15 and the rotor 32a of the second resolver 32 to the second shaft 18b, the second resolver 32 can rotate the input shaft 18 at its rotational position (steering angle) and reaction. The rotational position of the rotor 15a of the force compensation motor 15 can be detected.

The third resolver 33 has the same configuration as the first resolver 31 and the second resolver 32. More specifically, the third resolver 33 has a rotor and a stator although not shown. The rotor is coupled to the rotor 21 a of the steering assist motor 21 so as to be integrally rotatable, and the stator is fixed to the motor housing of the steering assist motor 21.
The lock mechanism 25 is for fixing the transmission ratio between the input shaft 18 and the output shaft 19 to a predetermined value (1 in the present embodiment) by locking the rotation of the carrier 57 at the time of failure.

FIG. 3A is a cross-sectional view of the main part of the lock mechanism 25, and shows a state where the lock mechanism 25 does not lock the carrier 57. 2 and 3A, the lock mechanism 25 includes a ring member 60 that is coupled to the third portion 57c of the carrier 57 so as to be integrally rotatable, and a rod 61a that can be engaged with the ring member 60. And a solenoid 61 having the same.
A plurality of grooves 60 a are arranged on the outer periphery of the ring member 60 at equal intervals in the circumferential direction. The solenoid 61 is attached to the housing 53. The solenoid 61 includes a rod 61a, an electromagnet, and a spring (not shown) that urges the rod 61a toward the ring member 60, and is driven and controlled by a steering control unit 38 (see FIG. 1).

  Referring to FIGS. 2 and 3B, when the vehicle is powered off, rod 61a is fitted into groove 60a of ring member 60 by the biasing force of the spring. Similarly, at the time of failure, the rod 61a is fitted in the groove 60a of the ring member 60. On the other hand, in the main mode, as shown in FIG. 3A, the rod 61 a is arranged at a position where it does not engage with the ring member 60 by driving the solenoid 61. As a result, the rod 61 a does not restrict the rotation of the carrier 57.

Referring to FIG. 2, when the steering member 2 is steered in the main mode, the input shaft 18 connected to the steering member 2 rotates. As a result, the input sun gear 54 of the transmission ratio variable mechanism 13 rotates.
At this time, the transmission ratio control unit 46 of the steering control unit 38 sets the targets of the transmission ratio control motor 14 and the reaction force compensation motor 15 based on input signals from the sensors 30 to 36 connected to the steering control unit 38. Set the drive amount. Then, the steering control unit 38 controls the transmission ratio control motor 14 and the reaction force compensation so that the deviation between the rotational positions of the rotors 14a and 15a of the transmission ratio control motor 14 and the reaction force compensation motor 15 and the target rotational position becomes zero. The motor 15 is driven.

Under the control of the steering control unit 38, the rotor 14a of the transmission ratio control motor 14 may not be rotated. In this case, each planetary gear 56, output sun gear 55, and output shaft 19 are rotated by the rotation of the input sun gear 54.
At this time, the rotation transmission ratio from the input shaft 18 to the output shaft 19 is the aforementioned predetermined transmission ratio (for example, 1). As a result, the steered wheels 11 are steered in the operation direction of the steering member 2 by an amount corresponding to the angle obtained by multiplying the steering angle of the steering member 2 by the rotation ratio. The transmission ratio to the steering wheel 11 is a constant value.

  On the other hand, when the carrier 57 is rotated by driving the transmission ratio control motor 14 under the control of the transmission ratio control unit 46 of the steering control unit 38, the rotation transmission from the input shaft 18 to the output shaft 19 is performed as described above. The transmission ratio is increased or decreased from the transmission ratio by the rotation of the carrier 57. As a result, the transmission ratio between the input shaft 18 and the output shaft 19, that is, the transmission ratio from the steering member 2 to the steered wheels 11 can be changed steplessly.

Further, the reaction force control unit 47 drives the reaction force compensation motor 15 in order to compensate for the reaction force applied to the steering member 2 due to the drive of the transmission ratio control motor 14. As a result, the reaction torque is transmitted to the input shaft 18 so as to cancel the torque fluctuation of the steering member 2 accompanying the drive of the transmission ratio control motor 14. This reduces the driver's uncomfortable feeling.
Next, the main control flow of the vehicle steering apparatus 1 will be described.

Hereinafter, (1) the flow of control for setting the abnormality determination mode, (2) the flow of control in the abnormality determination mode, and (3) the flow of control in the fail mode by the steering control unit 38 will be described. To do.
In the present embodiment, a flow of control related to abnormality determination of the first resolver 31 as a predetermined sensor will be described.

  FIG. 4 is a flowchart for explaining a flow of control for setting the abnormality determination mode (1). As shown in FIG. 4, when the ignition key of the vehicle is turned on (step S1), the mode setting unit 48 sets the main mode (step S2). Thereby, the above-described main mode for controlling the transmission ratio control motor 14 and the reaction force compensation motor 15 according to the traveling state of the vehicle is set.

Next, the steering control unit 38 reads a signal related to the traveling state from the traveling state sensor 36 (step S3). Examples of the signal relating to the running state in this case include a vehicle speed, a position signal of a shift lever of an automatic transmission (AT) car, and a signal of a side brake of the vehicle.
When the vehicle speed is zero, the shift lever is in the parking position, and it is determined that the vehicle is still stopped (YES in step S4), for example, because the side brake is applied, the steering control unit The mode setting unit 48 of 38 sets the abnormality determination mode (step S5).

Next, the abnormality determination mode (2) will be described. The abnormality determination mode is a mode for determining whether an abnormality has occurred in the first resolver 31. The abnormality determination mode includes a first abnormality determination mode and a second abnormality determination mode.
FIG. 5 is a flowchart for explaining the flow of control in the first abnormality determination mode. As shown in FIG. 5, in the first abnormality determination mode, the steering control unit 38 first reads the detection value θvgr1 of the first resolver 31 corresponding to the transmission ratio control motor 14 as a predetermined motor (step Q1). . At this time, as shown in FIG. 6A, the steered wheels 11 of the vehicle 100 are, for example, along the vehicle straight direction, and θvgr1 = 0.

  Subsequently, the steering control unit 38 rotates the rotor 14a of the transmission ratio control motor 14 in one direction (for example, clockwise as viewed from the steering member 2) for the first target angle δ1 (deg) (step Q2). The first target angle δ1 is, for example, about a few (deg) to 100 (deg). At this time, the transmission ratio control motor 14 is rotationally driven by open loop control that does not use the first resolver 31. Thereby, as shown in FIG. 6B, the steered wheels 11 of the vehicle 100 are rotated clockwise by an angle δ1 ′ corresponding to the first target angle δ1. That is, when the rotor 14a of the transmission ratio control motor 14 is rotated, this rotation is transmitted to the pinion 7a via the carrier 57, the output shaft 19 and the like, and the rack shaft 8 is displaced. Thereby, the steered wheel 11 of the vehicle 100 rotates clockwise.

  After the rotor 14a of the transmission ratio control motor 14 is rotated by the first target angle δ1 (deg) in one direction by open loop control, the first determination unit 49 reads the detection value θvgr2 of the first resolver 31 (step Q3). . Thereafter, the first determination unit 49 calculates the change amount Δθvgr1 = | θvgr1−θvgr2 | of the detected value of the first resolver 31 before and after the rotor 14a of the transmission ratio control motor 14 is rotated by the first target angle δ1 ( Step Q4).

  As shown in FIG. 6C, the turning angle θvgr1 ′ of the steered wheels 11 corresponding to the detection value θvgr1 of the first resolver 31 can be estimated from the detected value θvgr of the first resolver 31. Further, the turning angle θvgr2 ′ of the steered wheel 11 corresponding to the detected value θvgr2 of the first resolver 31 can be estimated. Further, it is possible to estimate the amount of shift Δθvgr1 ′ of the turning angle of the steered wheels 11 corresponding to Δθvgr1 = | θvgr1−θvgr2 |.

Next, the first determination unit 49 determines whether or not the first resolver 31 satisfies the fail condition (step Q5). Specifically, it is determined whether or not the difference | Δθvgr1−δ1 | between the change amount Δθvgr1 of the detection value of the first resolver 31 and the first target angle δ1 is equal to or smaller than the first reference value θ1. The first reference value θ1 is several tens of degrees, for example.
When the difference | Δθvgr1−δ1 | between the change amount Δθvgr1 of the detection value of the first resolver 31 and the first target angle δ1 is equal to or less than the first reference value θ1 (YES in step Q5), the detection value of the first resolver 31 It can be said that the change amount Δθvgr1 is substantially equal to the first target angle δ1. Therefore, it is determined that the first resolver 31 is normal and does not satisfy the fail condition. In this case, the first fail counter value no1_fail_cnt is not added, and the counter value cnt1 is incremented by 1 (step Q6).

  On the other hand, when the difference | Δθvgr1−δ1 | between the change amount Δθvgr1 of the detected value of the first resolver 31 and the first target angle δ1 exceeds the first reference value θ1 in step Q5 (NO in step Q5), It can be said that the change amount Δθvgr1 of the detection value of the first resolver 31 is significantly different from the first target angle δ1. For example, such a situation may occur when the rotor 31a of the first resolver 31 is idle with respect to the carrier 57. Therefore, the first determination unit 49 determines that an abnormality has occurred in the first resolver 31 and the failure condition is satisfied. In this case, 1 is added to the first fail counter value no1_fail_cnt (step Q7), and then 1 is added to cnt1 (step Q6).

  Next, the steering control unit 38 rotates the rotor 14a of the transmission ratio control motor 14 by an angle δ1 as a predetermined first return angle in the direction opposite to that in step Q2 (step Q8). Thereby, as shown in FIG. 6 (d), the steered wheel 11 is rotated counterclockwise by δ1 ′ corresponding to the first target angle δ1, and at a position immediately before the first abnormality determination mode is executed. Return.

Next, it is determined by the first determination unit 49 whether or not the counter value cnt1 has reached the first predetermined value c1 (step Q9). Steps Q1 to Q9 are performed, for example, at a cycle of 10 (msec). The first predetermined value c1 is 10, for example. If the counter value cnt1 is less than the first predetermined value c1 (NO in step Q9), the process returns to step Q1.
On the other hand, when steps Q1 to Q9 are repeated and the counter value cnt1 reaches the first predetermined value c1 (YES in step Q9), the steering control unit 38 determines whether or not the first fail counter value no1_fail_cnt is zero. Is determined (step Q10). If it is determined at step Q5 that the fail condition is satisfied even once and the first fail counter value no1_fail_cnt is not zero (NO at step Q10), the mode setting unit 48 sets the fail mode (step Q11). ).

  On the other hand, in step Q5, if the determination that the fail condition is satisfied has never been made and the first fail counter value no1_fail_cnt is zero (YES in step Q10), the process proceeds to step Q12. In step Q12, the steering control unit 38 rotates the rotor 14a of the transmission ratio control motor 14 in the opposite direction to that in step Q2 (θvgr1 + Δθvgr1) (deg).

  Here, the significance of providing step Q12 will be described. In the first abnormality determination mode, feedback control using the rotation angle sensor of the first resolver 31 is not performed. For this reason, there is a possibility that minute backlash is generated on the rack shaft 8 by driving the transmission ratio variable mechanism 13. In step Q12, | Δθvgr1-δ1 | in step Q5 is equal to or smaller than the first reference value θ1, and it is known that the first resolver 31 is normal. Therefore, the transmission ratio control motor 14 is feedback controlled using the first resolver 31. As a result, a minute backlash that is expected to occur through steps Q1 to Q9 is calculated as Δθvgr1 (= | θvgr1−θvgr2 |). Then, using this Δθvgr1, the steered wheel 11 is returned to the position before execution of the first abnormality determination mode. This is the purpose of step Q12.

Note that step Q12 is executed when the first resolver 31 is normal, and may be omitted. On the other hand, when θvgr1 after execution of the first abnormality determination mode is required to have higher reliability, step Q12 may be positively used. It is significant that the actual detection value (θvgr1 + Δθvgr1) is used instead of the target angle δ1.
After step Q12, the steering control unit 38 clears the counter value cnt1 and the first fail counter value no1_fail_cnt to zero (step Q13), and the mode setting unit 48 sets the second abnormality determination mode (step Q14). .

FIG. 7 is a flowchart for explaining the flow of control in the second abnormality determination mode. As shown in FIG. 7, in the second abnormality determination mode, the steering control unit 38 first reads the detection value θvgr3 of the first resolver 31 (step R1).
Next, the steering control unit 38 controls the solenoid 61 of the lock mechanism 25 to pierce the rod 61a into the groove 60a of the ring member 60 (step R2). Thereby, rotation of the ring member 60 is controlled.

Subsequently, the steering control unit 38 rotates the rotor 14a of the transmission ratio control motor 14 in one direction (for example, clockwise as viewed from the steering member 2) by the second target angle δ2 (deg) (step R3). The second target angle δ2 is a number (deg), for example, about 5 (deg).
At this time, the transmission ratio control motor 14 is rotationally driven by feedback control using the first resolver 31.

After the rotor 14a of the transmission ratio control motor 14 is rotated by the second target angle δ2 (deg) in one direction, the second determination unit 50 reads the detection value T0 ′ of the torque sensor 30 (step R4).
Next, the second determination unit 50 determines whether or not the torque sensor 30 satisfies the failure condition (step R5). Specifically, the detected value T0 ′ of the torque sensor 30 after the rotor 14a of the transmission ratio control motor 14 is rotated by the second target angle δ2 and a value obtained by multiplying the second target angle δ2 by a predetermined coefficient k (reference) It is determined whether or not the difference | k · δ2−T0 ′ | from the torque (k · δ2) is equal to or smaller than the second reference value T2. The second reference value T2 is, for example, 1 (N · m). The coefficient k is appropriately set according to the number of teeth of each gear 54, 55, 56 of the transmission ratio variable mechanism 13 and the torsional rigidity of the input shaft 18. As described above, the second reference value T2 is a small value of about 1 (N · m). Therefore, the rotation of the steering member 2 and the second shaft 18b of the input shaft 18 is substantially restricted by the frictional resistance that the second shaft 18b receives from a bearing or the like. At this time, the rotation angle θ of the rotor 14a of the transmission ratio control motor 14 and the torque T acting on the input shaft 18 are, for example, along the graph shown in FIG.

  As shown in FIG. 7, when | k · δ2-T0 ′ | is equal to or smaller than the second reference value T2 (YES in step R5), the detected value T0 ′ of the torque sensor 30 indicates that the rotor 14a is moved to the second target angle δ2. It can be said that it is substantially equal to the torque generated in the input shaft 18 when rotated. Therefore, it is determined that the torque sensor 30 is normal and does not satisfy the fail condition. In this case, the second fail counter value no2_fail_cnt is not added, and one counter value cnt2 is added (step R6).

  On the other hand, if the difference | k · δ2−T0 ′ | between the actual torque k · δ2 of the input shaft 18 and the detected value T0 ′ of the torque sensor 30 exceeds the second reference value θ2 in step R5 ( In step R5, NO), it can be said that the detected value T0 ′ of the torque sensor 30 is greatly different from the actual torque of the input shaft 18. For example, such a situation may occur when a member (such as a detection ring) that should be coupled to the input shaft 18 of the torque sensor 30 is idle with respect to the input shaft 18. Therefore, the second determination unit 50 determines that an abnormality has occurred in the torque sensor 30 and the failure condition is satisfied. In this case, 1 is added to the second fail counter value no2_fail_cnt (step R7), and then the process proceeds to step R6.

After 1 is added to the counter value cnt2 in step R6, the steering control unit 38 rotates the rotor 14a of the transmission ratio control motor 14 by δ2 as a predetermined second return angle in the opposite direction to that in step R3. (Step R8).
Thereby, the steered wheel 11 of the vehicle 100 is returned to the position before being steered in step R3.

  Next, it is determined by the second determination unit 50 whether or not the counter value cnt2 has reached the second predetermined value c2 (step R9). The second predetermined value c2 is 10, for example. When the counter value cnt2 is less than the second predetermined value c2 (NO in step R9), the process returns to step R3. On the other hand, when steps R3 to R9 are repeated and the counter value cnt2 reaches the second predetermined value c2 (YES in step R9), the steering control unit 38 determines whether or not the second fail counter value no2_fail_cnt is zero. Is determined (step R10). If it is determined at step R5 that the fail condition is satisfied even once and the second fail counter value no2_fail_cnt is not zero (NO at step Q10), the mode setting unit 48 sets the fail mode (step R11). ).

  On the other hand, in step R5, when it is not determined that the fail condition is satisfied and the second fail counter value no2_fail_cnt is zero (YES in step R10), the process proceeds to step R12. In step R12, the steering control unit 38 rotates the rotor 14a of the transmission ratio control motor 14 in the opposite direction to that in step R3 (θvgr3 + Δθvgr2) (deg).

  Here, the significance of providing step R12 will be described. In the second abnormality determination mode, the first resolver 31 is used. On the other hand, when the rotation of the ring member 60 is locked, the input shaft 18 and the output shaft 19 are connected via the transmission ratio variable mechanism 13 so that power can be transmitted. For this reason, there is a possibility that a minute backlash is generated on the rack shaft 18 after the steps R1 to R10 are finished due to the influence of the torsion bar 20 and the bearings supporting the shafts 18 and 19. Therefore, the transmission ratio control motor 14 is feedback-controlled, and the detection value θvgr4 (see FIG. 6E) of the first resolver 31 immediately after passing through R1 to R10 is read. Then, the minute backlash that is expected to have occurred through steps R1 to R10 is calculated as Δθvgr2 (= | θvgr3−θvgr4 |). Then, by rotating the rotor 14a of the transmission ratio control motor 14 by θvgr3 + Δθvgr2 in the opposite direction to that in step R3, the steered wheel 11 is moved to a position before executing the second abnormality determination mode (position corresponding to θvgr3). return. This is the significance of providing step R12.

  Step R12 is a step in a state where the torque sensor 30 is normal, in other words, a state where the backlash and the like are within the allowable range, and may be omitted. On the other hand, when θvgr3 after execution of the second abnormality determination mode is required to have higher reliability, step Q12 may be positively used. It is significant that the actual detection angle (θvgr3 + Δθvgr2) is used instead of the target angle δ2.

If Δθvgr2 is obtained using θvgr1 in the first abnormality determination mode, higher reliability in the turning angle of the steered wheels 11 after the end of the second abnormality determination mode can be secured.
After step R12, the steering control unit 38 clears the counter value cnt2 and the second fail counter value no2_fail_cnt to zero (step R13). Next, the lock of the ring member 60 by the rod 61a of the solenoid 61 is released (step R14), and the main mode is set by the mode setting unit 48 (step R15).
Note that steps R3 to R9 are performed, for example, at a cycle of 10 (msec).

  FIG. 9 is a flowchart for explaining the flow of control in the fail mode. As shown in FIG. 9, in the fail mode, first, the rotation of the carrier 57 is locked (step T1). Specifically, the solenoid 61 of the lock mechanism 25 is turned off. As a result, the rod 61a of the solenoid 61 enters the groove 60a of the ring member 60 by the biasing force of the spring, and the carrier 57 and the rotor 14a of the transmission ratio control motor 14 are locked (rotation restricted). Therefore, the rotation of the steering member 2 is transmitted to the input shaft 18 and the input sun gear 54, and further to the output sun gear 55 through the planetary gears 56 that can rotate and cannot revolve. The rotation of the output sun gear 55 is transmitted to the steering mechanism 9 through the output shaft 19 and the like, and as a result, the steered wheels 10 are steered.

Emergency steering when stopping the steering control and the reaction force control accompanying the occurrence of the failure can be performed by manual steering by mechanical power transmission from the steering member 2 to the steering mechanism 9.
Next, the supply of electric power to the transmission ratio control motor 14 and the reaction force compensation motor 15 is stopped (step T2).

Thus, the supply of current to the reaction force compensation motor 15 in addition to the transmission ratio control motor 14 is stopped. Since the feedback control of the transmission ratio control motor 14 using the first resolver 31 or the like is impossible, the reaction force compensation motor 15 is driven in a state where the reaction force control by the reaction force compensation motor 15 cannot be performed appropriately. Is preventing.
Next, the warning lamp 44 is turned on, and a warning sound is emitted from the speaker 45, so that the driver is informed of the transition to the fail mode (step T3). Thereby, it is possible to prompt the driver to store the vehicle in the maintenance shop.

  As described above, according to the present embodiment, the transmission ratio can be changed by driving the transmission ratio control motor 14 in the main mode. In addition, by driving the reaction force compensation motor 15, it is possible to compensate for fluctuations in the reaction force to the steering member 2 caused by driving the transmission ratio variable mechanism 13. Further, the steering assist motor 21 can be driven to assist the driver in steering the steering member 2. As a result, it is possible to give the driver a steering feeling without a sense of incongruity while realizing an appropriate transmission ratio according to the traveling state of the vehicle, and the driver can easily operate the steering member 2 with a small force. be able to.

  In the first abnormality determination mode, the transmission ratio control motor 14 is rotated by the steering control unit 38 in the predetermined rotation direction by the first target angle δ1. If there is no abnormality in the first resolver 31, the change amount Δθvgr1 of the detection value of the first resolver 31 is substantially the same value as the first target angle δ1. On the other hand, if the first resolver 31 is abnormal due to the rotor 31a of the first resolver 31 being out of the carrier 57 or the like, the change amount Δθvgr1 of the detected value of the first resolver 31 is the first target angle δ1. It will deviate greatly. Therefore, when the difference between the detected value variation Δθvgr1 of the first resolver 31 and the first target angle δ1 exceeds the first reference value θ1, it can be determined that an abnormality has occurred in the first resolver 31. .

Thereby, abnormality of the 1st resolver 31 can be detected more reliably. Moreover, since it is not the structure which provides the sensor for exclusive use for detecting the abnormality of the 1st resolver 31, a number of parts can be reduced and it is preferable also from the point of manufacturing cost.
As described above, since the abnormality of the first resolver 31 can be detected more reliably, the abnormality of the transmission ratio control caused by the abnormality of the first resolver 31 can be suppressed. The rotor 31a of the first resolver 31 may fall off from the carrier 57 due to vibrations, aging degradation, or the like when the vehicle travels on a rough road. At this time, if the output of the first resolver 31 is simply interrupted (becomes zero) and the abnormality of the first resolver 31 is detected, the output signal from the first resolver 31 even if the rotor 31a falls off. Therefore, the abnormality of the first resolver 31 cannot be detected.

  However, under such an abnormality, the first resolver 31 cannot detect the rotational position of the transmission ratio control motor 14. As a result, although the rotational position of the transmission ratio control motor 14 cannot be detected by the first resolver 31, a control current continues to flow through the transmission ratio control motor 14 in order to reach the target rotational position. This causes a failure in the ratio control motor 14.

  On the other hand, in the present embodiment, it is not simply determined whether or not the detected value θvgr of the first resolver 31 exceeds the threshold value, but the command value from the steering control unit 38 to the transmission ratio control motor 14 is determined. By comparing the first target angle δ1 and the change amount Δθvgr1 of the detected value θvgr of the first resolver 31, it can be determined whether or not an abnormality has occurred in the first resolver 31. Therefore, the abnormality of the first resolver 31 can be detected more reliably. For this reason, the rotational position of the transmission ratio control motor 14 can be detected with high reliability by the first resolver 31. As a result, when the transmission ratio control motor 14 reaches the target rotation position, the first resolver 31 detects that fact, and the feedback control that the control current to the transmission ratio control motor 14 stops can be reliably maintained.

Therefore, current does not continue to flow through the transmission ratio control motor 14 indefinitely. Thereby, failure of the transmission ratio control motor 14 can be suppressed, and appropriate transmission ratio control can be realized.
In addition, the steering control unit 38 determines whether the first resolver 31 is abnormal in the first determination unit 49, and then moves the rotor 14a of the transmission ratio control motor 14 to the first target angle in a direction opposite to the predetermined rotation direction. Rotate by δ1 or θvgr1 + Δθvgr1.

  In the present embodiment, since the transmission ratio control motor 14 is rotated when determining whether or not the first resolver 31 is abnormal, the steered wheels 11 also operate in conjunction with each other. Therefore, after the presence / absence of abnormality of the first resolver 31 is determined, the rotational position of the transmission ratio control motor 14 is returned to the position before the determination of the presence / absence of abnormality of the first resolver 31 or the straight traveling position. . Thereby, if the presence or absence of the abnormality of the 1st resolver 31 is determined, it can suppress giving a driver the uncomfortable feeling that the position of the steered wheel 11 which is not directly related will change.

  Further, although the first resolver 31 is checked for abnormality at the first predetermined value c1 at the maximum, the rotational position of the rotor 14a of the transmission ratio control motor 14 is changed every time when the presence or absence of abnormality of the first resolver 31 is determined. The state before the determination of whether or not the one resolver 31 is abnormal is restored (step Q8). Thereby, it is possible to prevent the direction of the steered wheels 11 from continuously changing in one direction every time it is determined whether or not the first resolver 31 is abnormal. Thereby, it can suppress that the determination of the presence or absence of this abnormality becomes impossible because the steered wheel 11 is most steered during the determination of the presence or absence of the abnormality of the first resolver 31.

Further, in the second abnormality determination mode, the second determination unit 50 determines that the reference torque k · δ2 and the torque when the transmission ratio control motor 14 is rotated by the steering control unit 38 in the predetermined rotation direction by the second target angle δ2. When the difference | k · δ2−T0 ′ | from the detection value T0 ′ of the sensor 30 exceeds the second reference value θ2, it is determined that an abnormality has occurred in the torque sensor 30.
In this case, torque is applied to the input shaft 18 by driving the transmission ratio control motor 14, and this torque is detected by the torque sensor 30. If an abnormality has occurred in the torque sensor 30, the detected value T0 ′ of the torque sensor 30 corresponds to this torque change even though the input shaft 18 is loaded with torque by driving the transmission ratio control motor 14. Does not change. Therefore, the abnormality of the torque sensor 30 can be detected more reliably.

  It is important for the transmission ratio variable control that the torque sensor 30 accurately detects the steering torque. Therefore, when an abnormality has occurred in the torque sensor 30, it is necessary to be able to detect it reliably. In this configuration, the abnormality of the torque sensor 30 can be reliably detected. As a result, it is possible to suppress the transmission ratio variable control from being performed due to an erroneous torque detection result.

In addition, the steering control unit 38 determines whether the torque sensor 30 is abnormal in the second determination unit 50, and then moves the transmission ratio control motor 14 by the second target angle δ2 or θvgr3 + Δθvgr2 in the direction opposite to the predetermined rotation direction. Rotate.
In this embodiment, when determining whether there is an abnormality in the torque sensor 30, the transmission ratio control motor 14 is rotated, so the steered wheels 11 also operate in conjunction with each other. Therefore, after the presence / absence of abnormality of the torque sensor 30 is determined, the rotational position of the transmission ratio control motor 14 is returned to the position before the presence / absence of abnormality of the torque sensor 30 is determined. Thereby, when the presence or absence of abnormality of the torque sensor 30 is determined, it is possible to suppress the driver from feeling uncomfortable that the position of the steered wheels 11 that is not directly related changes.

Further, when the steering control unit 38 determines that at least one of the first resolver 31 and the torque sensor 30 is abnormal, the steering control unit 38 drives the lock mechanism 25 to lock the rotation of the rotor 14a of the transmission ratio control motor 14. In addition, the drive of the transmission ratio control motor 14 and the reaction force compensation motor 15 is stopped.
As a result, the transmission ratio can be mechanically fixed by the lock mechanism 25 in a failure state where the transmission ratio control motor 14 and the reaction force compensation motor 15 cannot be accurately controlled. Thereby, the state in which the steering mechanism 9 can be operated by the steering member 2 can be maintained. Further, since the drive of the transmission ratio control motor 14 is stopped, it is possible to prevent the drive ratio control motor 14 from continuing to flow and failing.

The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims.
For example, in the above embodiment, the abnormality of the first resolver 31 is detected, but the present invention is not limited to this. In the first abnormality determination mode, an abnormality of the second resolver 32 may be detected. In this case, the second embodiment is the same as the above embodiment except that the predetermined sensor becomes the second resolver 32 and the predetermined motor becomes the reaction force compensation motor 15.

Further, in the second abnormality determination mode, the rotation of the input shaft 18a of the first shaft 18 may be regulated using the steering lock device 26. In the second abnormality determination mode, as shown in FIG. 10, the reaction force compensation motor 15 is provided on the first shaft 18 a of the input shaft 18, and the rotation of the reaction force compensation motor 15 is locked, whereby the input shaft 18 a You may regulate rotation of.
Further, when the transmission ratio control motor 14 cannot be controlled, the steering assist motor 21 may be used as a transmission ratio variable motor.

Moreover, although the structure which uses a resolver as a 1st sensor, a 2nd sensor, and a 3rd sensor was illustrated, it is not limited to this. As the first to third sensors, other general sensors that can detect the rotational positions of the corresponding motors 14, 15, and 21 may be used.
Furthermore, in the present embodiment, the column assist type steering assist mechanism 12 that applies the steering assist force from the output shaft 19 of the steering shaft 3 to the steering mechanism 9 has been described, but the present invention is not limited to this. For example, a configuration in which a steering assist force is applied to the steering mechanism 9 from the pinion shaft 7 or the rack shaft 8 may be employed.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering member, 9 ... Steering mechanism, 13 ... Transmission ratio variable mechanism, 14 ... Transmission ratio control motor, 15 ... Reaction force compensation motor, 18 ... Input shaft, 19 ... Output shaft, 25 DESCRIPTION OF SYMBOLS ... Lock mechanism, 30 ... Torque sensor, 31 ... 1st resolver (1st sensor), 32 ... 2nd resolver (2nd sensor), 37 ... Control part, 49 ... 1st determination part, 50 ... 2nd determination part, θreact—detection value of second resolver, θvgr—detection value of first resolver, Δθvgr1—change amount of detection value of first resolver (change amount of detection value of predetermined sensor), θ1—first reference value, δ1,. First target angle (first return angle), δ2 ... second target angle (second return angle), k · δ2 ... reference torque, T0 '... detected value of torque sensor, T2 ... second reference value.

Claims (4)

A transmission ratio variable mechanism that is interposed between an input shaft that rotates according to steering of the steering member and an output shaft that rotates in conjunction with the operation of the steering mechanism, and that can change the transmission ratio between the input shaft and the output shaft; ,
A transmission ratio control motor for changing the transmission ratio of the transmission ratio variable mechanism;
A first sensor for detecting a rotational position of the transmission ratio control motor;
A reaction force compensation motor for compensating a steering reaction force of the steering member due to the operation of the transmission ratio variable mechanism;
A second sensor for detecting a rotational position of the reaction force compensation motor;
A control unit for controlling the transmission ratio control motor and the reaction force compensation motor,
The control unit includes a first determination unit that determines whether there is an abnormality in a predetermined sensor including the first sensor or the second sensor,
In the case where the transmission ratio control motor or the reaction force compensation motor corresponding to the predetermined sensor is rotated by a first target angle in a predetermined rotation direction by open loop control by the control unit, the first determination unit When a difference between a change amount of a detection value of a predetermined sensor and the first target angle exceeds a first reference value, it is determined that an abnormality has occurred in the predetermined sensor ;
The control unit determines whether the predetermined sensor has an abnormality in the first determination unit, and then sets the transmission ratio control motor or the reaction force compensation motor corresponding to the predetermined sensor to the predetermined rotation direction. A function of rotating a first return angle equal to the first target angle by open loop control in the opposite direction;
When the first determination unit determines that the predetermined sensor is normal, the transmission ratio control motor or the reaction force compensation motor corresponding to the predetermined sensor is moved in a direction opposite to the predetermined rotation direction. The vehicle steering apparatus has a function of rotating at a rotation angle corresponding to the change amount of the detection value of the predetermined sensor by feedback control using the predetermined sensor . In Claim 1 , further comprising a torque sensor for detecting torque acting on the steering member,
The control unit includes a second determination unit that determines whether the torque sensor is abnormal when the first determination unit determines that the predetermined sensor is normal .
When the transmission ratio control motor is rotated by a second target angle in a predetermined rotation direction by the control unit, the second determination unit determines that a difference between a predetermined reference torque and a detected value of the torque sensor is a second reference A vehicle steering apparatus, wherein when the value is exceeded, it is determined that an abnormality has occurred in the torque sensor. According to claim 2, wherein, said after determining the presence or absence of an abnormality in the torque sensor in the second judging unit, said transmission ratio control motor, the second target angle in the opposite direction to the predetermined rotational direction A function of rotating a second return angle equal to
When the second determination unit determines that there is no abnormality in the torque sensor, the transmission ratio control motor is controlled in a direction opposite to the predetermined rotation direction by feedback control using the predetermined sensor. A vehicle steering apparatus having a function of rotating at a rotation angle corresponding to a change amount of a detection value of the predetermined sensor detected when the ratio control motor is rotated at the second target rotation angle . In any 1 paragraph of Claims 1-3, It further has a lock mechanism which can lock rotation of the transmission ratio control motor,
When it is determined that an abnormality has occurred in the sensor, the controller locks the rotation of the transmission ratio control motor by driving the lock mechanism and stops driving the transmission ratio control motor. A vehicle steering apparatus characterized by the above.

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